Fill in the blanks with appropriate items :
A radioactive substance decays 20% in 10 min if at start there are ` 5 xx 10^(20)` atoms present , after ________ hour the number of atoms will be reduced to ` 10^(18)`.

A radioactive substance decay 25% in 10 minutes . If at start there are 4 xx 10^(20) atoms present. After how much time will the number of atoms be reduced t0 10^(20) atoms? (given In 3=1.098)

A radioactive substance decay 25% in 10 minutes . If at start there are 4 xx 10^(20) atoms present. After how much time will the number of atoms be reduced t0 10^(20) atoms? (given In 3=1.098) a) 10.98 min b) 21.97 min c) 48.19 min d) None of these

Fill in the blanks with appropriate items : The half-life period of radioactive element _______ minute if 75% of it disintegrates in 40 min.

A radioative substance decays 10% in 5 days. The aamount remains after 20 days is [log 3 =0.4771]

Fill in the blanks: (-10) xx __ = 20

The half-life of a radioactive substance against alpha- decay is 1.2 xx 10^7 s . What is the decay rate for 4 xx 10^15 atoms of the substance ?

The half-life of a radioactive substance against alpha- decay is 1.2 xx 10^7 s . What is the decay rate for 4 xx 10^15 atoms of the substance ?

The half-life of a radioactive substance against alpha- decay is 1.2 xx 10^7 s . What is the decay rate for 4 xx 10^15 atoms of the substance ?

Fill in the blanks: 20-:(-10) = -( _)

A radioactive substance contains 10^(15) atoms and has an activity of 6.5 xx 10^(11) Bq. What is its half life.