What changes in the colour of iron nails and copper sulphate do you observe after keeping the iron nails dipped in copper sulphate solution for about 30 minutes?

6 State whether the following statement is true or False:

Non-metals react with dilute acids to produce a gas which burns with a ‘pop’ sound.

7 From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal:

(i) which reacts with water only on boiling, and

(ii) another which does not react even with steam.

9 What is aqua-regia ? Name two special metals which are insoluble in comman reagents but dissolve in aqua-regia. 10 Give the names and formulae of (a) two acidic oxides, and (b) two basis oxidics.