CBSE Class X – Science Chemistry Exam (Full Syllabus)

Identify the reducing agent in the following reactions: 2H₂O + 2F₂ → 4HF + O₂

Mention whether it is physical or chemical changes : Heating of an iron rod to red hot

Mention whether it is physical or chemical changes: Sublimation of solid ammonium chloride

Solid calcium oxide reacts vigorously with water to form calcium hydroxide, accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form a solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?

1. It is an endothermic reaction
2. It is an exothermic reaction.
3. The pH of the resulting solution will be more than seven.
4. The pH of the resulting solution will be less than seven

When hydrogen sulphide gas is passed through a blue solution of copper sulphate a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remain in the solution. The reaction is an example of a:

Which of the following substances will not give carbon dioxide on treatment with dilute acid?

Which of the subsequent phenomena occur, when a slight amount of acid is added to water?

1. It turns lime water milky
2. It extinguishes a burning splinter.
3. It dissolves in a solution of sodium hydroxide.
4. It has a pungent odour

The source of oxyalic acid is

The chemical used for cleaning swimming pools

Common name calcium sulphate hemihydrate

An element X is forming acidic oxide. Its most expected position in the modern periodic table is:

Which of the following are the characteristics of isotopes of an element?

1. Isotopes of an element have the same atomic masses.
2. Isotopes of an element have the same atomic number
3. Isotopes of an element show the same physical properties.
4. Isotopes of an element show the same chemical properties.

Arrange these elements in increasing order of their atomic radii

Which is not true about the noble gases?

Is calcium?

What is denatured alcohol?

The number of covalent bonds in the molecule of ethane.

A saturated hydrocarbon undergoes complete combustion and burns with

UnSaturated hydrocarbons contains

The next homologue of C₂H₄

2 ml each of conc. HCl, HNO₃, and a mixture of conc. HCl and conc. HNO3 in the ratio of 3:1 were taken in test tubes labelled as : A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C. The metal could be:

1. AI
2. Au
3. Cu
4. Pt

When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding potassium metal to water catches fire.

Why should we not throw small pieces of sodium into a sink in the laboratory? Because of

Give the formula of the stable binary compounds that would be formed by the combination of following pair of elements: Al and Cl₂

When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (molecular mass = 40) and liberates a gas Z which easily catches fre. Identify X, Y and Z.