A marble block of mass 2 kg lying on ice when given a velocity of 6 m/s is stopped by friction in 10 s. Then the coefficient of friction is (Take g= 10 ms-2)


A) 0.06

B) 0.03

C) 0.04

D) 0.01


A hydrogen atom is an exciting state of principal quantum number (n), it emits a photon of wavelength ($\lambda$). when it returns to the ground state. the value of n is 

A) $\sqrt{\frac{\lambda R}{\lambda R-1}}$

B) $\sqrt{\frac{(\lambda R-1)} {\lambda R}}$

C) $\sqrt{\lambda(R-1)}$

D) $\sqrt{\frac{\lambda R}{\lambda R-1}}$


 If the nuclear radius of 27 Al is 3.6 Fermi, the approximate nuclear radius of 64Cu  in Fermi is

A) 4.8

B) 3.6

C) 2.4

D) 1.2


 The half-life of radioactive Radon is 3.8 days. the time at the end of which 1/20 th of the radon sample will remain undecayed is (given  $\log_{10}e=0.43434 $)

A) 3.8 days

B) 16.5 days

C) 33 days

D) 76 days


 An unpolarized beam of intensity  I0 is incident on a pair of nicols making an angle of 60° with each other. The intensity  of light emerging from the pair is 

A) $I_{0}$

B) $I_{0}$/2

C) $I_{0}$/4

D) $I_{0}$/8