<span>From the above given choices :
melting is an endothermic process</span>
In this reaction 50% of the compound decompose in 10.5 min thus, it is half life of the reaction and denoted by symbol
.
(a) For first order reaction, rate constant and half life time are related to each other as follows:

Thus, rate constant of the reaction is
.
(b) Rate equation for first order reaction is as follows:
![k=\frac{2.303}{t_{1/2}}log\frac{[A_{0}]}{[A_{t}]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt_%7B1%2F2%7D%7Dlog%5Cfrac%7B%5BA_%7B0%7D%5D%7D%7B%5BA_%7Bt%7D%5D%7D)
now, 75% of the compound is decomposed, if initial concentration
is 100 then concentration at time t
will be 100-75=25.
Putting the values,

On rearranging,

Thus, time required for 75% decomposition is 21 min.
Since there is one carbon with 4 Fluorines attached to it, and both compounds are no metals, we use the covalent method for naming,
Here we ignore the prefix for the first element if it is 1. Mono. Then pay attention to the second one, it would be tetra, because tetra means 4. Here there are 4 fluorines.
Drop ine and place ide
CF4 = carbon tetrafluoride.