Nuclei — Physics STD 12 Science — Question

A radioactive material undergoes decay by ejecting electrons. The electron ejected in this process is:

In an amplitude modulated wave for audio frequency of 500 cycle/second, the appropriate carrier frequency will be(a) 50 cycles/sec(b) 100 cycles/sec(c) 500 cycles/sec(d) 50,000 cycles/sec

A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is(a) 0.5 ohm(b) 1.5 ohm(c) 1.25 ohm(d) 4/5 ohm

For goldplating on a copper chain, the substance required in the form of solution is(a) Copper sulphate(b) Copper chloride(c) Potassium cyanide(d) Potassium aurocyanide

The working of optical instruments like camera, microscope, telescope, etc. having glass lenses is based on a phenomenon of light. Identify the phenomenon.

A medium is said to be dispersive, if(a) Light of different wavelengths propagate at different speeds(b) Light of different wavelengths propagate at same speed but has different frequencies(c) Light is gradually bent rather than sharply refracted at an interface between the medium and air(d) Light is never totally internally reflected

How can we explain the reddish appearance of sun at sunrise or sunset? 

Some radioactive nucleus may emit(a) Only one α,β or γ at a time(b) All the three α,β  and  γ one after another(c) All the three α,β  and γ  simultaneously(d) Only α and β  simultaneously