ْ (Marks : 8x ½ =4) Parts of speech : قَ

أ

ْس ٌم -

1 )إ ِ

ٌ ْ

)2

ِ

-

3َ )ظ ْ ٌ -

4َ ِ )ظ ٌ -

-

ٌ

5َ )ظ ِ ْ

- ِ ْ

ِ

ا

ْس ُمم إْ

6 )إ ِ

-

ِّر

َظ

ا

ْ ُم إْ

ُم ُم

)7

َظ ْ ِ -

ا

ْ ُم إْ

ُم ُم

)8​

the answer is x=1 . but I don't understand the choose

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.

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.