391. The chemical (Ethyl Mercaptan) added to the otherwise odourless LPG cooking gas for imparting a detectable smell to the gas is a compound of:_______?
A. Bromine
B. Fluorine
C. Chlorine
D. Sulphur

392. Marsh gas is_______?
A. Nitrogen
B. Ethane
C. Methane
D. Hydrogen

393. Potassium Permanganate is used for purifying drinking water, because_________?
A. It is a sterilising agent.
B. It dissolves the impurities of water.
C. It is a reducing agent.
D. It is an oxidising agent.

394. Find the PH of a 0.001 M solution of Nitric acid HNO3?
A. 2
B. 3
C. 4
D. 5

395. Which set of quantum numbers is not allowed?
A. n=2,l=1,m1=0,ms=+1/2
B. n=2,l=1,m1=-1,ms=+1/2
C. n=2,l=0,m1=0,ms=-1/2
D. n=2,l=2,m1=1,ms=-1/2

396. The purpose of Smelting an ore is to________?
A. Reduce it
B. Oxidize it
C. Obtain an alloy
D. Separate volatile impurities

397. Which Oxide of Manganese is amphoteric?
A. MnO2
B. Mn2O3
C. Mn2O7
D. MnO

398. A process used for the Concentration of Ore is________?
A. Roasting
B. Forth flotation
C. Electrolysis
D. Distillation

399. Which metal is used as a reducing agent in Smelting______?
A. C
B. Zn
C. Al
D. Cu

400. Parke’s process is used in the extraction of________?
A. Iron
B. Sodium
C. Silver
D. Zinc