Qn 11.

Balance the following chemical equations.

a) Mg + O₂ → MgO

b) Na + O₂ → Na₂O

c)Mg(OH)₂ + H₂SO₄ → MgSO₄ +H₂O

d) KClO₃ → KCl+ O₂

Qn 12.

The chemical equation given below represents the reaction between hydrogen and oxygen producing water.

H₂ + O₂ → H₂O

Is the given equation balanced? Give reason.

Qn 13.

From the statements given below ,find the wrong one. Rewrite it correctly.

a) In a chemical reaction mass is neither created nor destroyed.

b) The total mass of the products will be greater than the total mass of the reactants.

c) In a chemical reaction ,the total number of atoms of each element in the reactant side and that in the product side are equal.

Qn 14.

A few chemicals are given .

 

NaCl, AgNO3, Na2S2O3, BaCl2, HCl

 

a. Choose the suitable chemicals from the box and plan an experiment to prove that temperature influences the rate of reaction

b. What is your observation?

c. Which is the substance formed as a result of the reaction taking place?

Qn 15.

Name the catalyst which reduces the rate of decomposition of hydrogen peroxide?

Qn 16.

Take two test tubes A and B. Take equal volumes of sodium thiosulphate solution in both test tubes. Heat test tube A. Add equal volumes of dilute hydrochloric acid in both test tubes.

a. In which test tube the reaction is faster?

b. Which is the factor that affects rate of reaction here?.

c. Explain why the rate of reaction is faster in this test tube

Qn 17.

14 Take 5ml hydrogen peroxide (H₂O₂ ) solution in a test tube. Add some MnO₂ into it..

a. Which is the gas evolved ?How will you identify it?

b.What is the function of MnO₂ in this reaction?

Qn 18.

Which one of the following does not affect the rate of reaction?

(temperature, pressure, colour of reactants, concentration)

Qn 19.

Take 5ml of hydrogen peroxide (H₂O₂) solution in a test tube. Add some manganese dioxide (MnO₂ ) into it.

a. Which is the gas evolved ?

b. What is the function of MnO₂ in this reaction?

c. Which are the substances remaining in the test tube when the reaction is over?‍

Qn 20.

IMAGE

Analyse the figure given above and answer the following questions.

a. Identify the gas formed in this reaction?

b. In which beaker the rate of reaction is faster? Give reason

c. Suggest any other method to increase the rate of collision?

Qn 21.

Analyse the given reaction and answer the following questions.

CaCO₃ + 2HCl → CaCl₂ + H₂O + ------X-------

a. Which is the product X formed here ?

b. Suggest any two methods to increase the amount of products in the given reaction

Qn 22.

Analyse the figure given below and answer the following questions.

IMAGE

a. In which test tube is the rate of reaction faster?

b. Which is the factor that influences the rate of reaction in this case?

c. Write down the balanced chemical equation of the reaction taking place here.

Qn 23.

Zn⁰ + Cu²⁺(SO₄)₂^2- → Zn²⁺(SO₄)₂ ^2-+ Cu⁰

Analyse the given equation and answer the following questions.

a. Which element gets oxidised?

b.Which element /ion gets reduced?

c. Which is the oxidising agent?

d. Which is the reducing agent?

Qn 24.

Examine the given reaction

Fe + 2HCl → FeCl₂ + H₂

Does this reaction represent a redox reaction ?Justify your answer

Qn 25.

Choose oxidation reactions from the following and write them.

i) Zn → Zn²⁺ + 2e^-

ii) F + 1e ^-→ F ^-

iii) Cl +1e^- → Cl^-

iv) Mg→ Mg²⁺ + 2e^-

Qn 26.

Unbalanced and incomplete chemical equations are given. Fill up the gaps by selecting from the formulae of the molecules given in brackets.Also balance the given equations.

a) Zn + 2HCl  → --a--  +  H₂

b) 2Mg + --b-- →  2MgO

c) 4Al +3O₂  →  _-----c_-----

(hint: O₂,  ZnCl₂,  Al₂O₃)

Qn 27.

Hydrogen peroxide decomposes to give oxygen.

A student wrote the chemical equation of this reaction as follows.

H₂O₂→ H₂O + O

a) Which are the reactants and products in this reaction? .

b)Are the molecular formulae of reactants and products written here correct ? If not rewrite them correctly.

c)write the balanced chemical equation for this reaction.

Qn 28.

NaCl + AgNO₃→ NaNO₃ + AgCl

When 58.5g NaCl reacts completely with 170g AgNO₃ , 85g NaNO₃ is formed.Calculate the mass of AgCl formed in this reaction? Justify your answer.

Qn 29.

.Find the relation and fill up suitably

Atomic theory : John Dalton

Law of conservation of mass: ..................

Qn 30.

Mg⁰ + 2H⁺¹Cl^-1 → Mg⁺²Cl₂^-1 + H₂⁰

Analyse the given chemical equation and answer the following questions.

a) Which atom/ ion gets oxidised?

b) Which atom/ ion gets reduced?

c) Which is the oxidising agent ?

d) Identify the reducing agent?