English Medium कक्षा १० - CBSE Question Bank Solutions

During the reaction of some metals with dilute hydrochloric acid, following observations are made.

Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.

Why do we store silver chloride in a dark coloured bottle?

Zinc liberates hydrogen gas when reacted with dilute hydrochloric acid whereas copper does not. Explain why?

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.

1.  Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
2. Name the black substance formed and give its chemical formula.

What happens when zinc granules are treated with dilute solution of H₂SO₄, HCl, HNO₃, NaCl and NaOH Also write the chemical equations if reaction oçcurs.

On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained :

1. Write a balanced chemical equation for the reaction involved.
2. What other name can be given to this precipitation reaction?
3. On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?

You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO₃, ZnCl₂ and water. In which of the above containers, can these solutions be kept?

“All plants give out oxygen during the day and carbon dioxide during the night”. Do you agree with this statement? Give a reason.

Two green plants are kept separately in oxygen-free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.

Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?

Explain the importance of soil for plant growth.

In the redox reaction:

MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂

State whether the given chemical reaction is a redox reaction or not. Justify your answer.

\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]

A reddish brown metal used in electrical wires when powdered and heated strongly turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information answer the following questions:

1. Name the metal and the black substance formed.
2. Write balanced chemical equations for the two reactions involved in the above information

State the change in colour observed in following case mentioning the reason:

Copper powder is strongly heated in air.

What is the purpose of making urine in the human body?

Name the organs that store and release the urine.

Give the structural formula of ethanol.

A carbon compound 'P' on heating with excess conc. H₂SO₄ forms another carbon compound 'Q' which on addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound 'R'. One molecule of 'R' on combustion forms two molecules of carbon dioxide and three molecules of water. Identify P, Q and R and write chemical equations for the reactions involved

Name the compound formed when ethanol is heated in excess of conc. sulphuric acid at 443 K. Also, write the chemical equation of the reaction stating the role of conc. sulphuric acid in it. What would happen if hydrogen is added to the product of this reaction in the presence of a catalyst such as palladium or nickel?