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Metals and Non-metals: CBSE Class 10 Chemistry practice questions

Practise 50 questions on Metals and Non-metals, free, with an explanation for each answer.

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Sample questions

A student heats one end of a metal wire. The other end gets hot quickly. Which two metals are the best conductors of heat?

A metal wire clamped on a stand and heated at one end with a pin stuck on the far end with wax
  1. Lead and mercury
  2. Silver and copper
  3. Iron and aluminium
  4. Gold and sodium
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B. Silver and copper

Silver and copper are the best conductors of heat. Lead and mercury are comparatively poor conductors, which is why they are the usual wrong choice. Metals in general conduct heat well and have high melting points, so the wire does not melt in the flame.

About 2 km of gold wire can be drawn from 1 g of gold. How much wire could be drawn from 5 g of gold?

A metal drawn through a die into a thin wire
  1. 2.5 km
  2. 7 km
  3. 10 km
  4. 0.4 km
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C. 10 km

Length is proportional to mass: 5×2 km=10 km5 \times 2\ \text{km} = 10\ \text{km}. The traps: dividing instead of multiplying (2÷52 \div 5 is far too small, and 5÷2=2.55 \div 2 = 2.5 uses the wrong ratio) and adding (2+5=72 + 5 = 7) as if the masses were lengths.

Sodium reacts with cold water: 2 Na+2 HX2O→2 NaOH+HX2\ce{2Na + 2H2O -> 2NaOH + H2}. Suppose 4 mol of sodium react completely. How many moles of hydrogen gas are released?

A piece of sodium racing on water with hydrogen burning above it
  1. 2 mol
  2. 4 mol
  3. 1 mol
  4. 8 mol
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A. 2 mol

The balanced equation shows 2 mol Na→1 mol H22\ \text{mol Na} \to 1\ \text{mol H}_2, so 4 mol Na→2 mol H24\ \text{mol Na} \to 2\ \text{mol H}_2. Traps: assuming a 1:1 ratio (4 mol), copying the 1 mol of H2\text{H}_2 straight from the equation without scaling it up (1 mol), or doubling instead of halving (8 mol).

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