Answer:
<h3>
Merits of modern periodic table:</h3>
- The wrong position of some elements like argon, potassium, cobalt and nickel due to atomic weights have been solved by arranging the elements in the order of increasing atomic number without changing their own places.
- The isotopes of some element have the same atomic numbers. Therefore, they find the same position in periodic table.
- It separates metals from non-metals.
- The groups of the table are divided into sub groups A and B due to their dissimilar properties which make the study of elements specific and easier.
- The representative and transition elements have been separated.
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Answer: <span>The molecules of a substance which must have the
<u>a</u></span>
<u>bility to move past one another</u> are said to be flexible.
Explanation: Those substances are said to be flexible which can be
bent without breaking. There are many substances which are
hard in nature but still can be bent. The hardness of such materials is due to
strong interactions between the molecules and the flexibility comes due to their
amorphous backbone. Therefore, greater the
crystalline level of macromolecules lesser is the flexibility and greater the amorphous character greater is the flexibility and vice versa. Also, the flexibility of polymers is increased by adding
plastisizers in it. Plastisizers make the hard polymers flexible by breaking the crosslinkers and enabling the macromolecules to move past one another.
Answer:
Density is 2.7 grams
Explanation:
formula for density is p= mass over volume [p being density]. So all you have to do is divide