Which of the following represents a chemical change?

1. Magnetization of iron
2. Condensation of liquid
3. Burning of fuel
4. Rusting of iron

Select the correct answer using the code given below:

• 1 and 2

• 2 and 3

• 3 and 4

• 1 and 4

Which one among the following is the correct order of reactivity of the elements?

• Cu > Mg> Zn> Na

• Na> Zn> Mg> Cu

• Cu> Zn > Mg> Na

• Na> Mg> Zn> Cu

Vinegar is produced from

• ethanoic acid

• valeric acid

• methanoic acid

• butanoic acid

244.

Which one of the following statements is correct?

• Only electrons reside inside the nucleus of an atom

• Both electrons and protons reside inside the nucleus of an atom

• Only neutrons reside inside the nucleus of an atom

• Both protons and neutrons can reside inside the nucleus of an atom.

The ratio of the velocity of X-rays to that of gamma rays

• is < 1

• is > 1

• is 1

• depends upon the ratio of their frequencies

Which one among the following is the main ingredient in cement?

• Gypsum

• Lime stone

• Clay

• Ash

Glass is actually:

• a crystalline solid

• an ionic solid

• an elastic solid

• a vitrified liquid

Solutions in test tubes containing H2O and aqueous NaOH can be differentiated with the help of

• red litmus

• blue litmus.

• Na₂CO₃

• HCI (aqueous)

A student heated some sulphur in a spatula and collected the gas 'X'. Which one among the following is correct about 'X'?

• X is SO₂ and it turns moist litmus to blue

• Xis SO₃ and it turns moist litmus to red

• X is SO₂ and it turns moist litmus to red

• X is SO₃ and it turns dry litmus to blue

The human stomach produces acid 'X' which helps in the digestion of food. Acid 'X' is:

• acetic acid

• methanoic acid

• hydrochloric acid

• citric acid