Let a and b be real numbers such that sin sin a +  b = 1/√2 and cos a + cos b = √6/2 then the value of sin (a + b) is :

(A)   1/2√2

(B)   1/√3 

(C)   √3/2

(D)   2/√3

How benzene is converted into n-propyl benzene 

(A) Friedel-crafts Alkylation 

(B) Friedel-crafts Acylation 

(C) Friedel-crafts Alkylation followed by clemmensen reduction 

(D) Friedal-crafts Acylation followed by clemmensen reduction

Two tunning forks P and Q when set vibration, gives 4 beats s^-1 . If a prong of the fork P is filled, the beats are reduced to 2 beats s^-1 . What is frequency of P, if that of Q is 250 Hz? 

(a) 250 Hz 

(b) 246 Hz 

(c) 252 Hz 

(d) 254 Hz

Which of the following type of forces are present in vulcanised rubber? 

(a) Weakest intermolecular forces 

(b) Hydrogen bonding 

(c) Three dimensional network of bonds 

(d) Metaluc bonding

Which of the following electron has minimum energy?

(A) n = 3, l = 2, m = –2, s = +1/2

(B) n = 4, l= 0,  m = 0, s = +1/2

(C) n = 4, l= 1, m = +1, s = +1/2

(D) n = 5, l = 0, m = 0, s = + 1/2

Van der waals’ real gas, acts as an ideal gas atwhich condition? 

(a) High temperature. low pressure 

(b) Low temperature, high pressure 

(c) High temperature, high pressure 

(d) Low temperature, low pressure 

Gravitational force acts on a particle due to fixed uniform solid sphere. Neglect other forces. Then particle : 

(A) experiences a force directed along the radial direction only. 

(B) always moves normal to the radial direction 

(C) always moves in the radial direction only. 

(D) always moves in circular orbit.

The addition of Br₂ to (E) – but – 2 – ene gives 

(A) (R, R) 2 – 3- dibromobutane 

(B) (S, S) – 2 – 3 – dibromobutane 

(C) (R, S) – 2 – 3 – dibromobutane 

(D) a mixture of (R, R) and (S, S) 2, 3 dibromobutane 

How many σ bonds and π bonds are present in

(A) 5 σ + 8 π 

(B) 9 σ + 7 π 

(C) 9 σ + 9 π 

(D) 5 σ + 9 π

Which of the following are addition polymers? 

(a) Nylon 

(b) Melamine formaldehyde resin 

(c) Orlon 

(d) All of these