CBSE
Multiple Choice QuestionsThe major role of fluorspar (CaF2) which is added in small quantity in the electrolytic reduction of alumina dissolved in fused cryolite (Na3AlF6) is
I. as a catalyst.
II. to make the fused mixture very conducting.
III. to lower the temperature of melting.
IV. to decrease the rate of oxidation of carbon at the anode.
I, II
II, III
I, II, III
III, IV
Noble gases are used in discharge tubes to give different colours. Reddish-orange glow is due to
Ar
Ne
Xe
Kr
Which of the following metals, Fe, Zn, Pb, Ag and Pt do not give a metal nitrate on treatment with concentrated HNO?
Fe and Zn.
Fe and Pt.
Pb, Ag and pt.
Fe, Ag and Zn.
When aqueous ammonia is added to green solution of nickel chloride, the colour changes to:
yellow
purple
violet
violet
Which of the following molecules forms no inter molecular hydrogen bonds?
HF
The oxidation number of sulphur atoms in peroxomonosulphuric acid H2SO5 and peroxodisulphuric acid H2S2O8, respectively are:
+8 and +7
+6 and +6
+4 and +6
+3 and +3
The correct order of acid strength is
HClO < HClO2 < HClO3 < HClO4
HClO4 < HClO < HClO2 < HClO3
HClO2 < HClO3 < HClO4 < HClO
HClO4 < HClO3 < HClO2 < HClO
Sodium sulphite is used in preserving squashes and other mildly acidic foods due to
potassium salt has preservative action
potassium metabisulphite prevents oxidation
potassium metabisulphite is not influcenced by acid
sulphur dioxide and sulphurous acid formed, kill bacteria and germs
Organophosphorus compounds are the most toxic insecticides. The common organophosphorus insecticides is:
Methoxy chlor
Dieldrin
Parathion
Malathion
T-shaped inter halogen compound is:
ClF3
ICl
ClF5
IF5
