English Medium कक्षा १० - CBSE Important Questions for Science

When lead nitrate is heated strongly in a boiling tube, two gases are liberated and a solid residue is left behind in the test tube.

1. Name the type of chemical reaction and define it.
2. Write the name and formula of the coloured gas liberated.
3. Write the balanced chemical equation for the reaction.
4. Name the residue left in the test tube and state the method of testing its nature (acidic/basic).

Write balanced chemical equation for the following word equation.

Lead nitrate + Potassium iodide → Lead iodide + Potassium nitrate

Is this a double displacement reaction? Justify your answer. Name the compound precipitated and write the ions present in it.

Write the method of preparation of Ca(OH)₂. What happens when CO₂ is passed through it? Write balanced chemical equation for the reaction involved.

Write two methods of preventing the rusting of iron.

Why is sodium kept immersed in kerosene oil?

An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be:

Food cans are coated with tin and not with zinc because ______.

Give reasons:

Platinum, gold and silver are used to make jewellery.

Write the name and formula of a molecule made up of three atoms of oxygen.

No chemical reaction takes place when granules of a solid, A, are mixed with the powder of another solid, B. However when the mixture is heated, a reaction takes place between its components. One of the products, C, is a metal and settles down in the molten state while the other product, D, floats over it. It was observed that the reaction is highly exothermic.

(i) Based on the given information make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of reaction.

(ii) Mention any two types of reactions under which above chemical reaction can be classified.

Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines.

Give reason:

Sodium, potassium and lithium are stored under oil.

Explain the following: 

Reactivity of aluminium decrease if it is dipped in nitric acid.

What is "rusting"? Describe with a labelled diagram an activity to investigate the conditions under which iron rusts.

Where does the metal aluminium, used in the process, occurs in the reactivity series of metals?

Answer the following question.

List two properties of alloys.

Arrange the following metals in the increasing order of their reactivities:

Copper, Zinc, Aluminium, and Iron

Write the chemical equation for the following reaction:
Calcium metal reacts with water.

Write the chemical equation for the following reaction:
Cinnabar is heated in the presence of air.

Write the chemical equation for the following reaction:
Manganese dioxide is heated with aluminum powder.