61.
ML2T-2 is the dimensional formula for

62.
Solar eclipse will take place when

63.
Isotopes of an element contain

65.
Sir C.V. Raman was awarded Nobel Prize for his work connected with which of the following phenomenon of radiation?

66.
In which of the following industries is mica as a raw material?

67.
Radiocarbon dating technique is used to estimate the age of

69.
Large astronomical telescopes always use as objective

70.
One should not connect a number of electrical appliances to the same power socket because