Wednesday, August 5, 2015

Chemistry

Q1. With reference to ionic compounds,consider the following statements:

1) Ionic compounds are insoluble in alcohol.

2) Ionic compounds in the solid state are good conductors of electricity.

Which of these statements is /are correct ?

a) Only 1 
b)Only 2
c)Both 1 and 2 
d)Neither 1 nor 2

ANSWER: a) Only 1

Explanation-Ionic compounds are insoluble in non –polar solvent, but are soluble in water and other polar solvent .Ionic compounds donot conduct electricity in solid state because the ions occupied fixed positions and are not able to have free movement .Thus ionic compounds are bad conductors of electricity in solid state but are good conductor of electricity in molten or dissolved state.


Q2.A change in which one or more new substances are formed is called.

a) Physical change 
b) Chemical change 
c) Both of them
d) None

ANSWER: b) Chemical change

Explanation-A chemical change is also called as chemical reaction and it is irreversible.


Q3.The process of depositing a layer of zinc on iron is called.

A) Ionization
B) Crystallization
C) Galvanization
D) Neutralization 

ANSWER: C) Galvanization

Explanation-Galvanization prevents rusting of iron.


Q4.Salts of which of the following elements provide colours to fireworks?

a) Zinc and sulphur
b) Potassium and mercury
c) Strontium and barium
D) Chromium and nickel

ANSWER: c) Strontium and barium

Q5.Consider the following statements:

1) Reactions in which energy is absorbed are known as Endothermic Reactions.
2) Zinc and lead are less reactive elements than copper.

Select the incorrect option.:

a) 1 only
b) 2 only
c) Both
d) None

ANSWER: b) 2 only

Explanation-zinc and lead are more reactive than copper .Thus they displace copper from its compounds.



Q6. Consider the following

1. Oxides of Hydrogen
2. Oxides of Nitrogen
3. Oxides of Sulphur

Which of the above causes acid rains?

a) 1 and 2
b) 3 only
c) 2 and 3
d) 1,2 and 3

ANSWER: c) 2 and 3

Explanation- Acid rain is caused by emissions of compounds of ammonium,carbon, nitrogen and sulphur which reacts with the water molecules in the
Atmosphere to produce acids.


Q7.An aqueous solution of copper sulphate is acidic in nature because the salt undergoes.

a) Dialysis
b) Electrolysis
c) Hydrolysis
d) photolysis

ANSWER: c) Hydrolysis 

Q8.With reference to the uses of washing soda.

1. Washing soda is used in glass , paper and soap industries.
2. It is not used in the manufacture of Borax.
3. It can be used as a cleaning agent.
4. It is unable for removing permanent hardness of water.

Choose the correct options:

a) 1,2 and 3
b) 2 and 3
c) 3 only 
d) 1 an 3 only

ANSWER: d) 1 an 3 only 

Explanation-It is used in the production of borax that is sodium compounds and can be easily used for removing permanent hardness of water.

Q9.Which one of the following pairs of metals constitutes the lightest metal and the heaviest metal,respectively?

a) Lithium and mercury
b) Lithium and osmium
c) Aluminium and osmium
d) Aluminium and mercury

ANSWER: b) Lithium and osmium

Explanation-Lithium lightest metal and osmium heaviest metal.


Q10.Which one of the following is used as an explosive?

a) Phosphorus trichloride
b) Mercuric oxide
c) Graphite
d) Nitroglycerine

ANSWER: d) Nitroglycerine

Explanation-Nitroglycerine is a heavy ,colourless , oily, explosive liquid obtained by nitrating glycerol .It is a very active compound in the manufacturing of explosives like Dynamite etc.

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