Given :
a. 
b. 
c. 
d. 
.
To Find :
Find the most likely vale of x for each one .
Solution :
a .
Because boron have valency of 3 .
So , x = 3 .
b .
Valency of carbon is 4 .
x = 4 .
c .
Valency of nitrogen is 3 .
Therefore , x = 3 .
d .
Now ,we know valency of carbon is 4 and hydrogen is 1 .
Also , two hydrogen are already there .
So , only 2 electrons left to share .
Since , chlorine have valency of 1 .
Therefore , only 2 electrons of chlorine can connect .
x = 2 .
Hence , this is the required solution .
Answer : The concentration of the 
solution is, 2.16 M
Explanation :
To calculate the concentration of base, we use the equation given by neutralization reaction:
where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is .
We are given:
Putting values in above equation, we get:
Thus, the concentration of the solution is, 2.16 M
According to an article dated back in February 8, 1992 which is entitled, “Science: Stardust is made of diamonds” on a website called newscientist (https://www.newscientist.com/article/mg13318073-000-science-stardust-is-made-of-diamonds/), American astronomers believed that diamonds are made in supernova explosions. It was said that the diamonds were the foundation of uncommon combinations of isotopes found in some meteorites. Donald Clayton of Clemson University in South Carolina suggested that the weightiest isotopes were more common in meteorites for the reason that the rare gases shaped in the neutron-rich outcome of a supernova explosion. Clayton also said, “the observed mixture of isotopes could have been produced only during the collapse of a massive star to form a neutron star”. This happens in a Type II explosion, for example the Supernova 1987A in the Large Magellanic Cloud. And rare gases like xenon become stuck in both weighty and light isotopes after the ejected gas from such a supernova cools down enough to create dust. The existence of the diamonds with these unusual gases in meteorites infers an alike source. Some of the carbon in the supernova fragments produces ordinary graphite dust, whereas some produces diamond dust. Considerable amount of stardust may be made of diamonds, if Clayton was not mistaken.
