1. Ethane (C2H6 ) on complete combustion gave CO2 and water. It shows that the results are in accordance with the law of conservation of mass. Then, the coefficient of oxygen is equal to ?

7/2

5/2

3

2

Answer: 7/2

Explanation:


2. In an electrolytic cell where electrolysis is carried, anode has ?

Connected to negative terminal of the battery

Negative charge

Positive change

None of these is correct

Answer: Positive change

Explanation:


3. In which of the following chemical equations the abbreviations represent the correct states of the reactants and Products involved at reaction temperature ?

2H2(l) +O2(l) -> 2H2O (g)

2H2(g) +O2(l) -> 2H2O (l)

2H2(g) +O2(g) -> 2H2O (l)

2H2(g)+O2(g) -> 2H2O(g)

Answer: 2H2(g) +O2(g) -> 2H2O (l)

Explanation:

It is because, the standard state for hydrogen and oxygen is gas and for water is liquid at reaction temperature.


4. What type of chemical reactions take place when electricity is passed through water ?

Decomposition

Double displacement

Displacement

Combination

Answer: Decomposition

Explanation:


5. A substance ‘X’ is used in white-washing and is obtained by heating limestone in the absence of air. Identify ‘X’ ?

CaCO3

CaOCl2

CaO

Ca (OH)2

Answer: CaOCl2

Explanation:


6. Electrolysis of water is a decomposition reaction. The molar ratio of hydrogen and oxygen gases liberated during electrolysis of water is Problems ?

1 : 2

1 : 1

4 : 1

2 : 1

Answer: 2 : 1

Explanation:


7. Which one of the following processes involve chemical reactions ?

Keeping petrol in a china dish in the open

Heating copper wire in presence of air at high temperature

Liquefaction of air

Storing of oxygen gas under pressure in a gas cylinder

Answer: Heating copper wire in presence of air at high temperature

Explanation:


8. Which one of the following processes involve chemical reactions ?

Keeping petrol in a china dish in the open

Heating copper wire in presence of air at high temperature

Liquefaction of air

Storing of oxygen gas under pressure in a gas cylinder

Answer: Heating copper wire in presence of air at high temperature

Explanation:


9. The brown gas evolved on heating of copper nitrate is ?

O2

NO2

N2

NO

Answer: NO2

Explanation:


10. MnO2 + 4HCl -> MnCl2 + H2O + Cl2 The oxidising agent is ?

Ag + Zn(NO3)3

MnCl2

MnO2

HCl

Answer: MnO2

Explanation:

MnO2 is oxidising agent because it is removing hydrogen from HCl to form Cl2