QUESTION PAPER - 5
Total Mark : 80
Section-A
Answer the following Q. No. 1 to 18 (with following Q. No. 1 to 18 (within the limit of 10 to 20 words) as directed : (1 mark each)
Fill in the blanks so as to make each of the following statement true:
1.The addition of oxygen to a substance is called ..oxidation........
2.All information from our environment is detected by the specialized..nerve........cells.
3. Genetics... is the science of heredity and evolution.
4. Size of Na+ is .smaller. than sodium atom.
State whether the following statement are true or false.
5. A neutron has a positive charge of 1.6 x 10-19C.false
6. Secretion of exocrine glands is known as hormone.false
7. Ethanoic acid is used in the manufacture of textiles.true
Choose the correct option and write it with answer from those given below multiple
choice questions : (MCQs)
8. Select the eco-friendly activity among the following:
(a) Using car for transportation
(b) Using polybags for shopping
(C) Using dyes for colouring clothes
(d) Using windmills to generate power for irrigation
9.In an ecosystem, the 10% of energy available for transfer from one trophic level to the
next is in the form of
(a) heat energy (b) light energy
(c) chemical energy (d) mechanical energy
10. Which is the ultimate source of energy?
(a) Water (b) Sun (c) Uranium (d) Fossil fuels
11. Which of the following statement is incorrect?
(a) For every normone there is a gene
(b) For every protein there is a gene
(c) For production of every enzyme there is a gene
(d) For every molecule of fat there is a gene
Answer the following questions as directed :
12. In which type of eye defect far point of eye gets reduced?myopia
13. Write the name and symbol of the element from the description.
The atom having the smallest size.hydrogen
14. What is a beam of light?
a bundle of light Ray's is called a beam of light
15. What is the common name of ethanoic acid? acetic acid
16. What is the full form of IUCD? Intra -utrine contraceptive device
Section : B
Answer the following questions Q. no. 17 to 26 (within the limit of 40 to 50 words)
directed : (2 marks each)
17. What is universal indicator? State the purpose for which this indicator is used.
Universal Indicator is the mixture of indicators.
It is used to detect whether the solution or a substance is acidic or basic.
The ph scale is used to identify it with the help of colour the colour of scale also tells the ph level.
18. State two ways to prevent the rusting of iron.
Answer :- Two ways to prevent the rusting of iron are: Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes water proof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented. Galvanisation: An iron article is coated with a layer of zinc metal, which prevents the iron to come in contact with oxygen and moisture. Hence, rusting is prevented.
19.State two main characteristics of elements on which modern periodic table is based?
No fixed position can be assigned to hydrogen in the periodic table. Why?
The physical and chemical properties of the elements
are periodic function if their atomic numbers.
Then the key factors for the designing of periodic
table are,
1. Periodicity in physical and chemical
properties
2. Atomic number
No fixed position can be assigned to hydrogen in the periodic table because it shows similarity with the elements present in group 1 as well as in group 18.
OR
19. Give reasons for the following statements:
a. Cations are smaller in size than the corresponding atom,
b. Size of the atom increases as we move down a group.
c. Atomic size decreases as we move across a period,
Answer :- a. Cations are smaller in size than the corresponding atom,
==>because they are formed by loss of electrons
b. Size of the atom increases as we move down a group.
==>Beacause as we move across a period, atomic radius decreases.
c. Atomic size decreases as we move across a period,
==>because, within a period or family of elements, all electrons are added to the same shell. However, at the same time, protons are being added to the nucleus, making it more positively charged.
20. Describe in brief the function of kidneys, ureters, urinary bladder and urethra.
Answer :- The kidneys form the urine and account for the other functions attributed to the urinary system. The ureters carry the urine away from kidneys to the urinary bladder, which is a temporary reservoir for the urine. The urethra is a tubular structure that carries the urine from the urinary bladder to the outside.
OR
20. What do the following transport:
a. Xylem
b. Pulmonary artery
C. Pulmonary vein
d. Vena cava
Answer :- (a)Xylem = Transport water and dissolved minerals implants.
(b)Phloem = Transport prepared food in plants.
(c)Pulmonary vein = Transport oxygenated blood from lungs to left ventricle of hearts.
(d)Vena cava = Transport deoxgenated blood from body to right ventricle.
21. How is the process of pollination different from fertilization?
Answer :- The process of transfer of pollen from the male parts (anther) of a flower to the female part (stigma) of the same or different flower is called as pollination. Whereas the fertilization is the common process, involving the union of the male gamete (sperm) and female gamete (egg)
22. List four properties of the image formed by a plane mirror.
Answer:- Four characteristics of images formed by a plane mirror are:
* Size of the object is always equal to the size of images formed.
* The image formed is virtual and erect.
* The image is laterally inverted.
* The distance between the object and mirror is equal to the distance between the mirror and image.
23. What are the causes of resistance in a conductor?
Answer :- An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.
OR
23. State the advantages of heating effect of current in daily life.
Answer :- Advantages of Heating effect of current:
1. The heating effect of electric current is put to good use in room heaters and water heating coils where electricity is converted into heat energy.
2. An electric bulb also exploits the effect. The filament of the bulb is made of Tungsten metal, which glows when heated by the electric current flowing through it, thus giving out light.
3. An electric fuse also uses the heating effect of electric current. A fuse is rated for a specific amperage. When the current through it exceeds its rating, the heat produced melts the fuse wire thus opening the circuit.
24. List in tabular form, major differences between an electric motor and a generator.
The differences between an electronic motor and a generator are as given below ;
25. What are trophic levels? Give an example of a food chain and state the different trophic
levels in it.
Answe :- Trophic level is the functional level occupied by an organism in a food chain. Examples the first trophic level is occupied by producers or the autotrophs which fix solar energy and prepare food. The second trophic level includes 'herbivores'. The carnivores occupy the successive levels.
26. Suggest three ways to maintain a balance between environmental and development to
survive.
The three ways to maintain a balance between environment and development to survive are :
(i) Forest resources should be used in an environmentally and developmentally sound manner.
(ii) Instead of using non-renewable natural resources use of renewable natural resources should be preferred.
(iii) Waste water generated by industries should be recycled.
OR
26.List any two causes of our failure to sustain availability of underground water.
Answer:
Loss of vegetation cover.
Diversion for high water demanding crops.
Pollution from industrial effluents.
Dumping of urban waste.
Section : C
Answer the following Q. no. 27 to 34 in short (within the limit of 60 to 80 words) as
directed. (3 marks each)
27. How can a balanced equation be made more informative? Explain with examples.
A chemical equation can give more informations in the following ways:
The physical state of the reactants and products can be indicated by putting (s) for solid, (l) for liquid, (g) for gas and (aq) for aqueous state.
Evolution or absorption of heat during the reaction can be denoted by adding or subtracting a heat term on the product side.
Temperature, pressure and catalyst can be indicated above the arrow (→ or =) separating the reactants and products.
Concentration of reactants and products are indicated by adding word (dil) for dilute and (cone) for concentrated before their formulae.
By the sign → or \rightleftharpoons information about irreversible and reversible reactions can be obtained.
28. Explain physical properties of metals and non-metals.
Physical Properties metals :
• Metals occur in the solid state. All metals are
solid except with an exception for mercury which
is in liquid state in its natural form.
• Metals are malleable in nature. They can be
beaten into thin sheets. For example, elements
such as aluminium, gold, and silver can be
beaten into thin sheets for common usage
purpose.
• Metals are ductile. This means that metals
can be stretched into thin wires. We can make
copper wires and aluminium wires. All metals
are equally ductile. Only that some metals are
more ductile than others for which they are used
for day to day purposes.
• Metals conduct heat and electricity. It is by
virtue of this property of metals that heat, and
electricity can pass through them. Every metal is
a good conductor of heat and electricity.
Physical Properties nonmetals:
• Non-metals are brittle and break into pieces
when beaten. Example: Sulphur and
phosphorus.
• Non-metals are not ductile so, they cannot
be made into thin wires.
• • Non-metals are insulators or poor
conductors of electricity and heat because they
do not lose electrons to transmit the energy.
• At room temperature, they can be in the
state of solids, liquids or gases.
They are non-sonorous.
• • They can be transparent.
OR
28. Explain corrosion with examples.
Corrosion is a process where the metal corrodes. Corrosion is a natural process and in the presence of a moist atmosphere, chemically active metals get corroded. Contrary to popular belief, rusting and corrosion are not the same.
Rusting is the process where iron corrodes due to exposure to the atmosphere. Corrosion is a process where the water or the moisture on the surface of the metal oxidizes with the atmospheric oxygen, it is an oxidation reaction. The main circumstance of corrosion occurs with iron because it is a structural material in construction, bridges, buildings, rail transport, ships, etc. Aluminum is also an important structural metal, but even aluminum goes under oxidation reactions. However, aluminum doesn’t corrode or oxidize as rapidly as its reactivity suggests. An alloy of aluminum or any other metal like magnesium can make aluminum stronger, stiffer and harder.
The alkali metals like sodium need to be stored in oil as they corrode quickly. Less reactive metals like lead and copper are used to roof situations. Copper (Cu) corrodes and forms a basic green carbonate and lead corrodes to form a white lead oxide or carbonate.
29. Why is abscisic acid known as stress hormone?
Answer :- Abscisic acid is called stress hormones as it induces various responses in plants against stress conditions.It increases the tolerance of plants toward various stresses. It induces the closure of the stomata during water stress. It promotes seed dormancy and ensures seed germination during favourable conditions. It helps seeds withstand desiccation. It also helps in inducing dormancy in plants at the end of the growing season and promotes abscission of leaves, fruits, and flowers.
30.What is placenta? Give the significance of placenta.
Answer :- The placenta is an organ attached to the lining of your womb during pregnancy.It keeps your unborn baby's blood supply separate from your own blood supply, as well as providing a link between the two. The link allows the placenta to carry out functions that your unborn baby can't perform for itself.
Oxygen and nutrients pass from your blood supply into the placenta. From there, the umbilical cord carries the oxygen and nutrients to your unborn baby. Waste products from the baby, such as carbon dioxide, pass back along the umbilical cord to the placenta and then into your bloodstream, for your body to dispose of them.
The placenta produces hormones that help your baby grow and develop. The placenta also gives some protection against infection for your baby while it's in the womb, protecting it against most bacteria. However, it doesn't protect your baby against viruses.
Alcohol, nicotine and other drugs can also cross the placenta and can cause damage to your unborn baby.
Towards the end of your pregnancy, the placenta passes antibodies from you to your baby, giving them immunity for about 3 months after birth. However, it only passes on antibodies that you already have.
31. How is the equal genetic contribuation of male and female parents ensured in the progeny?
Answer :- Equal genetic contribution of male and female parents in the progeny is ensured by the equal inheritance of chromosome from each parent. Human possesses 23 pairs of chromosomes, of which 22 pairs are autosomes and 1 pair is the sex chromosomes. The two sex chromosomes in human are X and Y. Females have 2 X chromosomes and males have a X and Y chromosome. During the process of fertilization, a haploid sperm fuses with a haploid ovum to produce a diploid zygote. Zygote receives equal amount of genetic material from each parent and thus, retains the diploid nature on fertilization.
OR
31. How are the areas of study - evolution and classification - interlinked?
Answer :- Evolution and classification are interlinked with each other. Classification is the most important term to explain evolution. Classification is based on the similarities and differences between two species or among two organisms. More closer the characteristics are, the more closer is the evolution and more chances are to remain in the same group of classification. We can appreciate that classification of species is in fact a reflection of their evolutionary
relationship.
32. Write any three points of difference between concave and convex mirrors.
FFERENCES
There are many differences between concave and convex mirrors and some of them are as follows.
If inner side of spherical mirror is reflecting, it is called as concave mirror. If outer side of the spherical mirror is reflecting, it is called as convex mirror.
IMAGE
Concave mirrors form real and inverted images.
Convex mirrors form virtual and erect images.
NATURE
The images formed by the concave mirrors are magnified in nature. The images formed by the convex mirrors are diminished in nature.
SIZE
The object in the image formed by the concave mirror look bigger than the original size of the object.
The object in the image formed by the convex mirror look smaller than the original size of the object.
POSITION
Concave mirrors form real and inverted images except when the object is between pole and focus.
Convex mirrors form virtual and erect images irrespecive of the position of the object.
EXAMPLES
The examples of concave mirrors are the mirrors used in automobile head lights, reflecting telescopes, torch lights, etc.
The examples of convex mirrors are the mirrors used as rear side mirrors of vehicles, optical instruments, calling bell, etc.
USAGE
Concave mirror is used in the solar furnace, the sun rays are focused at a point by the concave mirror.
The concentrated beam of sunlight at a point increases the temperature at that point. Convex mirror is used as the rear mirror of the vehicles because, the convex mirror enables a driver to view large area of traffic behind him by forming a small image of the vehicles.
OR
32. With the help of a ray diagram show the position, size amd the nature of the image
Formation of image by a convex mirror:
(i) Object between pole and infinity: As shown in Fig.
(a), an object AB is placed on the principal axis of a convex mirror. A ray AM passing parallel to the principal axis, after reflection, appears to come from the focus F. The ray AN passing through the centre of curvature C is reflected back along its own path. The two reflected rays appear to come from a common point A' behind the mirror. So A' is the virtual image of A. The line A'B' upon the principal axis is the complete image of AB. Hence a virtual, erect and diminished image is formed behind the mirror between Focus and Pole.
Fig.(a) Image formed by a convex mirror with the object between pole and infinity.
(ii) Object at infinity: When the object is placed at infinity, the incident parallel rays appear to diverge from the focus after reflection from the mirror, as shown in Fig (b). Hence a virtual, erect and extremely diminished image is formed behind the mirror.
Fig.(b). Image formed by a convex mirror with the object at infinity.
Table. Nature, size and position of images formed by a convex mirror
Nature
Position of the =1) between p and infinity
Size of the 2) infinity
Position of the the object image
1. Between P and F,behind the mirror
2.At the focus behind the mirror
Nature of the image
1.Virtual and erect
2. Virtual and erect
Size of the image
1.At infinity
2.Highly deminished point sized
33. To study the pontential differences across a combination of resistors in series.
(A) Resistors in Series
Resisors are said to be connected in series combinaton. If same current flows through each resistor when same potential difference is applied across the combination.
Consider the figure given below
In figure given above three resistors if resistance R1, R2 and R3 are connected ibn series combination.
If battery is connected across the series combination so as to mintain potential difference V between points A and B, the current I would pass through each resistor.
If V1, V2 andV3 is the potential difference across each resistor R1, R2 and R3 respectively, then according to Ohm's Law,
V1=IR1
V2=IR2
V3=IR3
Since in series combination current remains same but potential is divieded so,
V=V1+V2+V3
or, V=I(R1+R2+R3)
If Reqis the resistance equivalent to the series combination of R1, R2 and R3 then ,
V=IReq
where, Req=R1+R2+R3
Thus when the resistors are connected in series, equivalent resistance of the series combination is equal to the sum of individual resistances.
Value of esistance of the series combination is always greater then the value of largest individual resisnces.
For n numbers of resistors connected in series equivalent resistance would be
Req=R1+R2+R3+...........................+Rn
34. Define process of nuclear fission. Write the steps involved in generating electricity in a nuclear reactor.
Section : D
Answer the following 0. no. 35 to 39 in detail (within the limit of 90 to 120 won
directed : (4 marks each)
35. To find the angle of deviation of a ray of light passing through the prism
AIM
To trace the path of the rays of light through a glass prism.
MATERIALS REQUIRED
A drawing board, few drawing pins or cello-tape, a glass prism, a few sharp pointed alpins, three
sheets of white paper, a measuring scale, a pencil and a protractor.
PROCEDURE
Take a sheet of white paper and fix it on the drawing board with the help of a drawing pins or cello- tape.
Place a glass prism along its triangular base at middle on the paper. Mark the boundary ABC of the glass prism and then remove the prism.
Draw a thin dotted line XY along one of the refracting surfaces (say AB) as shown in the figure given below.
Draw a normal NFN1, i.e. perpendicular to line AB at F. Also, draw a line EF making an angle 30° to the normal. EF will act as the incident ray.
Place the glass prism back to its original position ABC.
Fix two alpins P1 and Q1 on line EF vertically by gently pressing their heads with thumb into the drawing board about 6 cm apart from each other.
Look the images of P1 and Q1 from the other refracting face AC. The images of pins P1 and Q1 appear to be at I1 and I2.
Fix two more alpins P2 and Q2 vertically such that the feet of the pins P2 and Q2 appear to be on the same straight line as the feet of the images I1 and I2 respectively. Confirm it by moving the head slightly to either side while looking them. All the pins P2, Q2 and image of P1 and Q1 would appear to move together if they are on the same straight line.
Remove the prism and all alpins. Mark the position of feet P2 and Q2 and also P1 and Q1 [like Θ],
Join the pin pricks P2 and Q2 and produce P2Q2 so that it meets the refracting side AC of the prism boundary at G. The line HG represents the path of the emergent ray.
Join F and G. The line FG represents the path of the refracted ray.
Repeat the experiment on different paper sheets by taking different values of angle of incidence, viz. 35°, 45°, 50° and 55°.
OBSERVATIONS
The ray of light entering from air to glass at the first refracting surface bends towards the normal after refraction. At the second refracting surface, the ray of light entering from glass to air bends away from the normal.
Thus, the ray of light suffers two refractions on passing through a prism and hence deviates through a certain angle from its original path.
RESULT
EFGH represents the path of light through the prism as shown in the figure drawn.
36. Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
Ans:
An electric generator converts mechanical energy into electrical energy.
Principle: It works on the principle of electromagnetic induction. whenever there is a change in the flux through any coil, there would be the induction of current.
Working:
An electric generator, as shown is consists of a rotating rectangular coil ABCD placed between the poles of a permanent magnet. The two ends of this coil are connected to the two rings R1 and R2. The inner side of the ring is made insulated. The two conducting stationary brushes B1 and B2 are kept pressed separately on the rings R1 and R2, respectively. The two rings R1 and R2 are internally attached to an axle. The axle may be mechanically rotated from outside to rotate the coil inside the magnetic field. Outer ends of the two brushes are connected to the galvanometer to show the direction of flow of current in the external circuit. When the axle attached to the two rings is rotated such that the arm AB moves up (and the arm CD moves down) in the magnetic field produced by the permanent magnet. Let us say the coil ABCD is rotated clockwise in the arrangement shown. By applying Fleming's right-hand rule, the induced currents are set up in these arms along the directions AB and CD. Thus an induced current flows in the direction ABCD. This means that the current in the external circuit flows from B2 to B1. After half a rotation, arm CD starts moving up and AB moving down. As a result, the directions of the induced currents in both the arms change, giving rise to the net induced current in the direction DCBA. The current in the external circuit now flows from B1 to B2. Thus after every half rotation the polarity of the current in the respective arms changes. Such a current, which changes direction periodically, is called alternating current (AC). This device is called an AC generator. To get a direct current (DC, which does not change its direction with time), a split-ring type commutator must be used. With this arrangement, one brush is at all times in contact with the arm moving up in the field, while the other is in contact with the arm moving down The function of Brushes: Brushes helps in transferring the current from inside the generator to the external circuit.
36. How will you show that the direction of the magnetic field depends on direction of the current through the conductor?
In a current carrying conductor direction of current determines the direction of magnetic field .Direction of magnetic field is governed by the 'right hand thumb rule'. Thumb points along the direction of the current Other fingers give the direction of the field Magnetic field Current
We can understand it by the following experiment :
Make connections according to following diagram
In diagram (a) and (b),
• The conductor is placed in N-S direction and
compass is placed in the same direction.
• When we change direction of current, needle
of the compass deflects in opposite
directions.
• Hence we concluded that current flowing in a
conductor produces magnetic field around it
and its direction depends on direction of
current in conductor.
37. Draw and explain excreatory system in human beings.
Answer:
The human excretory system is consists of kidneys (two), ureters (two), urinary bladder, and urethra.
Kidneys: These are reddish-brown bean-shaped organs which perform the main function of the formation of urine. Each kidney consisted of millions of nephrons which are the functional unit of the kidney. They help in performing three main processes involved in the formation of urine glomerular filtration, reabsorption, and secretion.
Ureters: Each kidney is connected with urinary bladder with the help of ureter. It is a long tube that carries urine formed in the kidney to the urinary bladder.
Urinary bladder: It is the organ where urine is stored until a voluntary signal is given by the central nervous system.
38. Explain chemical properties of carbon compounds.
Chemical Properties of Carbon Compounds
Combustion Reaction: Carbon and carbon compounds gives carbon dioxide, vapor, heat and light on burning in air. Following are some of the examples of combustion reaction of organic compounds:
C + O2 ⇨ CO2 + Heat + Light
CH4 + 2O2 ⇨ CO2 + 2H2O + Heat + Light
CH3C2OH + O2 ⇨ CO2 + H2O + Heat + Light
Chemical Properties of Carbon Compounds
Combustion Reaction: Carbon and carbon compounds gives carbon dioxide, vapor, heat and light on burning in air. Following are some of the examples of combustion reaction of organic compounds:
C + O2 ⇨ CO2 + Heat + Light
CH4 + 2O2 ⇨ CO2 + 2H2O + Heat + Light
CH3C2OH + O2 ⇨ CO2 + H2O + Heat + Light
Oxidation:
In combustion reaction, carbon compounds are oxidized in the presence of oxygen. The following example is different because alkaline KMnO4 is the oxidizing agent in this reaction.
CH3CH2OH + (Alkaline KMnO4/Acidified K2Cr2O7) ⇨ CH3COOH
Addition Reaction:
Formation of larger molecules by addition of more radicals is known as addition reaction. For example; ethene is converted into ethane when heated with the catalyst nickel.
CH2=CH2 + H2 + (Nickel catalyst) ⇨ CH3−CH3
When ethene undergoes addition reaction with chlorine, it gives dichloroethane.
addition reaction ethene and chlorine
Substitution Reaction:
Replacement of a functional group or any atom by another atom or functional group is known as substitution reaction. Substitution reactions are single displacement reactions.
When methane reacts with chlorine gas in the presence of sunlight, it gives chloromethane and hydrogen chloride.
CH4 + Cl2 + Sunlight ⇨ CH3Cl + HCl
Similarly, ethane gives chloroethane when it reacts with chlorine in the presence of sunlight.
C2H6 + Cl2 + Sunlight ⇨ C2H5Cl + HCl
39. Explain chemical properties of acids and bases.
Acids are a distinct class of compounds because of the properties of their aqueous solutions. Those properties are outlined below:
Aqueous solutions of acids are electrolytes, meaning that they conduct an electrical current. Some acids are strong electrolytes because they ionize completely in water, yielding a great many ions. Other acids are weak electrolytes that exist primarily in a non-ionized form when dissolved in water.
Acids have a sour taste. Lemons, vinegar, and sour candies all contain acids.
Acids change the color of certain acid-base indicators. Two common indicators are litmus and phenolphthalein. Blue litmus turns red in the presence of an acid, while phenolphthalein turns colorless.
Acids react with active metals to yield hydrogen gas. Recall that an activity series is a list of metals in descending order of reactivity. Metals that are above hydrogen in the activity series will replace the hydrogen from an acid in a single-replacement reaction, as shown below:
Zn(s)+H2SO4 (aq) => ZnSO4(aq) +H2 (g)
5. Acids react with bases to produce a salt compound and water. When equal moles of an acid and a base are combined, the acid is neutralized by the base. The products of this reaction are an ionic compound, which is labeled as a salt, and water.
Properties of bases
Aqueous solutions of bases are also electrolytes. Bases can be either strong or weak, just as acids can.
Bases often have a bitter taste and are found in foods less frequently than acids. Many bases, like soaps, are slippery to the touch.
Bases also change the color of indicators. Litmus turns blue in the presence of a base while phenolphthalein turns pink.
Bases do not react with metals in the way that acids do.
Bases react with acids to produce a salt and water.
OR
39.Explain strength of acid and base solutions.
Strong Acids
Strong acids completely dissociate in water, forming H+ and an anion. There are six strong acids. The others are considered to be weak acids. You should commit the strong acids to memory:
HCl: hydrochloric acid
HNO3: nitric acid
H2SO4: sulfuric acid
HBr: hydrobromic acid
HI: hydroiodic acid
HClO4: perchloric acid
If the acid is 100 percent dissociated in solutions of 1.0 M or less, it is called strong. Sulfuric acid is considered strong only in its first dissociation step; 100 percent dissociation isn't true as solutions become more concentrated.
H2SO4 → H+ + HSO4-
Weak Acids
A weak acid only partially dissociates in water to give H+ and the anion. Examples of weak acids include hydrofluoric acid, HF, and acetic acid, CH3COOH. Weak acids include:
Molecules that contain an ionizable proton. A molecule with a formula starting with H usually is an acid.
Organic acids containing one or more carboxyl group, -COOH. The H is ionizable.
Anions with an ionizable proton (e.g., HSO4- → H+ + SO42-).
Cations
Transition metal cations
Heavy metal cations with high charge
NH4+ dissociates into NH3 + H+
Strong Bases
Strong bases dissociate 100 percent into the cation and OH- (hydroxide ion). The hydroxides of the Group I and Group II metals usually are considered to be strong bases.
LiOH: lithium hydroxide
NaOH: sodium hydroxide
KOH: potassium hydroxide
RbOH: rubidium hydroxide
CsOH: cesium hydroxide
*Ca(OH)2: calcium hydroxide
*Sr(OH)2: strontium hydroxide
*Ba(OH)2: barium hydroxide
* These bases completely dissociate in solutions of 0.01 M or less. The other bases make solutions of 1.0 M and are 100 percent dissociated at that concentration. There are other strong bases than those listed, but they are not often encountered.
Weak Bases
Examples of weak bases include ammonia, NH3, and diethylamine, (CH3CH2)2NH. Like weak acids, weak bases do not completely dissociate in aqueous solution.
Most weak bases are anions of weak acids.
Weak bases do not furnish OH- ions by dissociation. Instead, they react with water to generate OH- ions.
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