Half-life period of a radioactive element is 100 yr. How long will it take for its 93.75% decay ?

1) 400 yr
2) 300 yr
3) 200 yr
4) 193 yr

 The time for half life period of a certain reaction A - Products is 1 hour. When the initial concentration of the reactant ‘A’, is 2.0 mol L
, how much time does it take for its concentration to come from 0.50 to 0.25 mol L^–1 if it is a zero order reaction? 

1)   4 h 
2)   0.5 h
3)  0.25 h
4)  1 h  

Which of the following represents soap ?

1) C₁₇H₃₅COOK
2) C₁₇H₃₅COOH
3) C₁₅H₃₁COOH
4) (C₁₇H₃₅COO)₂Ca

Electrolytic reduction of nitrobenzene in weakly acidic medium gives

1) N-Phenylhydroxylamine
2) Nitrosobenzene
3) Aniline
4) pHydroxyaniline

50 mL of each gas A and of gas B takes 200 and 150 s respectively for effusing through a pin hole under the similar conditions. If molecular mass of gas B is 36, the molecular mass of gas A will be

1) 96
2) 128
3) 32
4) 64

The starting material used in Solvay's process is

1)  Brine solution

2)  Sodium sulphate

3)  Carnallite

4)  All of them together

The bond energies of C−C, C=C, H−H and C−H linkages are 350, 600, 400 and 410 kJ/mol respectively. The heat of hydrogenation of ethylene is:

1) −170 kJ/mol
2) −400 kJ/mol
3) −260 kJ/mol
4) −460 kJ/mol

In the Reaction the product  C is

1) acetaldehyde
2) acetylene
3) ethylene
4) acetyl chloride

Which element's ionic radius is smaller than its atomic radius?

1. neon
2. nitrogen
3. sodium
4. sulfur

 In both DNA and RNA, heterocylic base and phosphate ester linkages are at –