Answer: Option (d) is the correct answer.
Explanation:
The amount of energy released when an electron is added to a neutral atom or ion preset in gaseous phase to form a negative ion then it is known as electron affinity.
As we move across a period, due to the decrease in size of atom there will be increase in electron affinity. And, when we move down a group then there will be decrease in electron affinity.
More positive is the value of electron affinity more readily the atom can gain an electron. And, more negative value of electron affinity means atom will have difficulty in gaining an electron.
Thus, we can conclude that the statement it tends to be more negative down a group correctly summarizes the trend in electron affinity.
Colloid: A substance of gelatinous consistency.
Mixture is a system where there are two or more substances which are mixed but not chemically bonded. Pure substance is any substance which is has only one component. Therefore, the following are classified as:
1.water = pure substance
<span>2.blood = mixture</span>
3.the oceans = mixture
4.iron =<span> pure substance</span>
5.brass = mixture
6.uranium = pure substance
7.wine = mixture
8.leather <span>= mixture</span>
9.table salt (NaCl) = pure substance