English Medium इयत्ता १० - CBSE Important Questions for Science

The colour of the solution observed after 30 minutes of placing zinc metal in copper sulphate solution is ______.

Dil. HCl is added to Zn granules. How will you prove that chemical change has taken place here? Support your response with two arguments.

A chemical reaction in which exchange of ions occurs between the reactants is known as ______.

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?

Write equations for the reactions of iron with steam. 

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.

Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

What are amphoteric oxides?

What happens when calcium reacts with water? Write the chemical equation of the reaction of calcium with water.

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.

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’?