LIWA

Metals and Non-metals

CBSE Class 10 · Science · Chapter 3

Past board exam questions

CBSE 2027 sample paper · 1 mark

Electrical wires made of aluminum

  1. corrode easily as aluminium is a very reactive metal.
  2. corrode easily because porous flaky aluminium oxide is formed.
  3. do not corrode easily as aluminium oxide forms a protective layer.
  4. do not corrode easily as aluminium is less reactive than metals like sodium, magnesium and zinc.
Show answer
do not corrode easily as aluminium oxide forms a protective layer.

CBSE 2027 sample paper · 4 marks

Aavya and Vihan are studying the properties of metals in school. They decide to design and conduct an experiment to test the relative conduction of heat by metals. They use the apparatus with rods of five different metals aluminium, silver, copper, iron and zinc attached to a central point. This central point is heated using a burner. The metal rods are of equal length and thickness. They observe that the candles at the end of the rods fall at different times. (Study the table) Time taken for the candle to drop: | Metal | Silver | Copper | Aluminium | Zinc | Iron | |---|---|---|---|---|---| | Time/s | 10 | 15 | 30 | 50 | 60 | A. On the basis of the table obtained, which metal is the best conductor of heat? B. Gold is a better conductor of heat than aluminium but it is not as good as copper. The time taken for the candle to drop if one of the rods were made of gold would have been: (i) 15 s (ii) 20 s (iii) 35 s (iv) 10 s C. The length of all the metal rods is increased by 20% without any change in the thickness. Will the time required for the candles to drop be affected? How and why?

Show answer
A. Silver – its candle drops first (10 s), so heat reaches the end of the silver rod fastest. B. (ii) 20 s – gold is a better conductor than aluminium (30 s) but poorer than copper (15 s), so its time must lie between 15 s and 30 s. C. Yes, the time required for the candles to drop will increase for all the metals; the order in which the candles fall will remain the same. In conduction, particles vibrate and pass heat on to one another, so heat takes more time to travel from one end to the other when it has to cover a longer distance.

CBSE 2027 sample paper · 4 marks

Aavya and Vihan are studying the properties of metals in school. They decide to design and conduct an experiment to test the relative conduction of heat by metals. They use the apparatus with rods of five different metals aluminium, silver, copper, iron and zinc attached to a central point. This central point is heated using a burner. The metal rods are of equal length and thickness. They observe that the candles at the end of the rods fall at different times. (Study the table) Time taken for the candle to drop: | Metal | Silver | Copper | Aluminium | Zinc | Iron | |---|---|---|---|---|---| | Time/s | 10 | 15 | 30 | 50 | 60 | A. On the basis of the table obtained, which metal is the best conductor of heat? B. Gold is a better conductor of heat than aluminium but it is not as good as copper. The time taken for the candle to drop if one of the rods were made of gold would have been: (i) 15 s (ii) 20 s (iii) 35 s (iv) 10 s D. Mayank tries the experiment with an apparatus similar to the one described above. He ensures the length of all metal rods is the same. However, the thickness of rods is not the same in his apparatus. Will the inference he draws on the basis of his experiment be correct? Justify your answer.

Show answer
A. Silver – its candle drops first (10 s), so heat reaches the end of the silver rod fastest. B. (ii) 20 s – gold is a better conductor than aluminium (30 s) but poorer than copper (15 s), so its time must lie between 15 s and 30 s. D. No, the inference will not be correct. For a fair comparison, only the metal should differ: all the dimensions of the rods (length and thickness) have to be the same. A thicker rod takes more time to conduct heat (to heat up to the end), so differences in thickness would change the times and the comparison of the metals would be wrong.

CBSE 2026 board paper · 1 mark

Which of the following metals is a poor conductor of heat ?

  1. Na
  2. Pb
  3. Cu
  4. Al
Show answer
Pb

CBSE 2026 board paper · 1 mark

Which of the following metals has a very low melting point ?

  1. Copper
  2. Sodium
  3. Aluminium
  4. Caesium
Show answer
Caesium

CBSE 2026 sample paper · 1 mark

Four statements about the reactions of oxides with dilute hydrochloric acid and aqueous sodium hydroxide are listed. I. Aluminium oxide reacts with both dilute hydrochloric acid and aqueous sodium hydroxide. II. Calcium oxide reacts with dilute hydrochloric acid and aqueous sodium hydroxide. III. Zinc oxide reacts with both dilute hydrochloric acid and aqueous sodium hydroxide. IV. Sulphur dioxide does not react with either dilute hydrochloric acid or aqueous sodium hydroxide. Which statements are correct?

  1. I and II
  2. I and III
  3. II and IV
  4. III and IV
Show answer
I and III

CBSE 2026 sample paper · 1 mark

An iron nail is added to each of the two test tubes ‘P’ and ‘Q’ containing aqueous copper (II) sulphate, and aqueous silver nitrate respectively. Which of the following observation is correct?

  1. In test tube ‘P’ iron nail is coated with a blue coating and in test tube ‘Q’ there is no reaction.
  2. Iron nail is coated with a brown coating in test tube ‘P’ and silver coating in test tube ‘Q’.
  3. There is no reaction in either of the test tubes ‘P’ or ‘Q’.
  4. There is no reaction in test tube ‘P’ but a silver coating on iron nail is seen in test tube ‘Q’.
Show answer
Iron nail is coated with a brown coating in test tube ‘P’ and silver coating in test tube ‘Q’.

CBSE 2026 board paper · 1 mark

Which of the following is an amphoteric oxide ?

  1. Na2O
  2. K2O
  3. CO2
  4. Al2O3
Show answer
Al2O3