CBSE Class 10 Science 2020 · Paper 31/2/2 · Question 26(b)

(a) (i) Sodium (potassium and lithium can also be cut with a knife) (ii) Iodine (iii) Mercury (iv) Gold (v) Silver (copper, the next best conductor, is also accepted) (vi) Carbon, as diamond, graphite and fullerene (sulphur and phosphorus also exist in different forms) (b) Alloys are generally harder and stronger than the pure metal, resist corrosion better, and have a higher electrical resistivity and a lower melting point, which suit them to uses the pure metal cannot serve (any two of these). Solder is an alloy of lead and tin ($\text{Pb}$ and $\text{Sn}$); an amalgam is an alloy in which one of the metals is mercury ($\text{Hg}$).