Science questions on Chemical Reactions and Equations

When 2 mL of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as :

Select from the following a decomposition reaction in which source of energy for decomposition is light:

MnO₂ + 4HCL → MnCl₂ + 2H₂O + Cl₂

The reaction given above is a redox reaction because in this case :

Two statements are given - One labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to the question from the codes (a), (b), (c) and (d) as given below :

Assertion (A) : Hydrogen gas is not evolved when zinc reacts with nitric acid.

Reason (R) : Nitric acid oxidises the hydrogen gas produced to water and itself gets reduced.

Name the type of chemical reaction in which calcium oxide reacts with water. Justify your answer by giving balanced chemical equation for the chemical reaction.

Write one chemical equation each for the chemical reaction in which the following have taken place :

(i) Change in colour

(ii) Change in temperature

(iii) Formation of precipitate

Mention colour change/temperature change (rise/fall)/compound precipitated along with equation.

Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction

Select from the following a process in which a combination reaction is involved :

The oxide which can react with HCl as well as KOH to give corresponding salt and water is

Consider the following cases : 
(a) CaSO₄ + Al →
(b) CuSO₄ + Ca →
(c) FeSO₄ + Cu →
(d) ZnSO₄ + Mg →

The cases in which new products will form are 

Identify the correct statement about the following reaction : 

2H₂S + SO₂ → 2H₂O + S 

Identify the product 'X' obtained in the following chemical reaction:

CaCO₃ $\stackrel{∆}{\to }$ 'X' + CO₂

A chemical compound used in glass, soap and paper industrives is

Consider the following Chemical equation:

a Al₂O₃ + b HCl → c AlCl₃ + d H₂O

In order to balance this chemical equation, the values of a, b, c and d must be 

Which one of the following reactions is different from the remaining three? 

This question consists of two statements - Assertion (A) and Reason (R), answer these questions selecting the appropriate option given below:

Assertion (A): A piece of Zinc metal gets reddish brown coating when kept in copper sulphate for some time.

Reason (R): Copper is more reactive metal than Zinc.

When magnesium is burnt in air, an ash of white colour is produced. Write chemical equation for the reaction giving the chemical name of the ash produced. State the type of chemical reaction giving justification for your answer.

State reasons for the following :

(a) Zinc oxide is an amphoteric oxide. 

(b) Sodium metal is stored in bottle filled with kerosene oil. 

(c) In the reactions of nitric acid with metals, generally hydrogen gas is not evolved. 

State giving reason the reduction process to obtain the following metals from their compounds 
(i) Mercury,
(ii) Copper and 
(iii) Sodium 

OR 

State giving reason for the change in appearance observed when each of the following metal is exposed to atmospheric air for some time : 
(i) Silver,
(ii) Copper and
(iii) Iron