1. Puneet Is writing some statements, choose the correct statement and help him ?

A chemical equation is a shorthand method of representing a chemical reaction.

The new substances produced in a reaction are known as products.

The substance which combine or react are known as reactants.

All the above.

Answer: All the above.

Explanation:

Here are all the statements are correct. Hence, your answer will be option [D].


2. Which of the following gases can be used for storage of fresh sample of an oil for a long time ?

Carbon dioxide or helium

Helium or nitrogen

Nitrogen or oxygen

Carbon dioxide or oxygen

Answer: Helium or nitrogen

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

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

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

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

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

Explanation:


4. Which of the following reactions will not take place ?

Zn + MgSO4 -> ZnSO4 + Mg

Mg + FeSO4 -> MgSO4 + Fe

2KBr + Cl2 -> KCl + Br2

Zn + CuSO4 -> ZnSO3 + Cu

Answer: Zn + MgSO4 -> ZnSO4 + Mg

Explanation:


5. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is ?

1 : 2

4 : 1

1 : 1

2 : 1

Answer: 2 : 1

Explanation:

The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is 2:1 by volume. In a decomposition reaction, a compound is broken down into its simpler forms. During electrolysis water is broken down into oxygen gas and hydrogen gas due to passing of electric current through it. You can easily understand by this equation: 2H2O (I) -> 2H2(g) + O2(g) The mole ratio of hydrogen and oxygen gases is 2:1 by volume.


6. MnO2 + 4HCl -> 2 + 2H2O + Cl2 Identify the substance oxidized in the equation ?

MnO2

MnCl2

HCl

H2O

Answer: MnO2

Explanation:

In this reaction HCl is oxidised to Cl2, whereas MnO2 is reduced to MnCl2.


7. Magnesium ribbon is rubbed before burning because it has a coating of ?

basic magnesium chloride

basic magnesium sulphide

basic magnesium carbonate

basic magnesium oxide

Answer: basic magnesium carbonate

Explanation:


8. Which of the following gases can be used for storage ?

Helium or Nitrogen

Carbon dioxide or Helium

Carbon dioxide or Oxygen

Nitrogen or Oxygen

Answer: Helium or Nitrogen

Explanation:


9. Which of the following gases can be used for storage ?

Helium or Nitrogen

Carbon dioxide or Helium

Carbon dioxide or Oxygen

Nitrogen or Oxygen

Answer: Helium or Nitrogen

Explanation:


10. Which Among The Following (Are) Double Displacement Reaction (S) ?

C + O2 -> CO2, and CH4 + 2O2 -> CO2 + 2H2O

Pb + CuCl2 -> PbCl2 + Cu, and Na2SO4 + BaCl2 -> BaSO4 + 2NaCl

Na2SO4 + BaCl2 -> BaSO4 + 2NaCl

Pb + CuCl2 -> PbCl2 + Cu, and CH4 + 2O2 -> CO2 + 2H2O

Answer: Na2SO4 + BaCl2 -> BaSO4 + 2NaCl

Explanation:

Double displacement reactions are such chemical reactions in which one component of each reactant exchange to form products. The cations and anions of two compounds exchange their ions to form two new compounds. Here only in reaction (C), ions of both reactants are exchanged and two entirely different compounds are formed.