1 Assertion (A): Potential energy of a body depends upon height of the body from the surface of earth.
Reason (R): Potential energy and height of the body from ground are directly proportional to each
other (h«<r)
a) Both A and R are true and R is the correct explanation of A
[ ]
b) Both A and R true and R is not the correct explanation of A
c) A is true but Ris false
d) A is false but R is true
beha

a

Explanation:

it increases with increasing height

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.