Correct Answer: C. electrovalent compound

Correct Answer: C) diamond and graphite

Explanation

Allotropes are different forms of the same element in the same physical state, but with different properties due to variations in the arrangement of atoms. Carbon is an element with several allotropes, which include diamond, graphite, amorphous carbon, and fullerenes.

In this question, the correct answer isOption C: diamond and graphite. Both diamond and graphite are well-known allotropes of carbon, and they differ in their properties due to the arrangement of carbon atoms in their structures.

Diamond is a hard, crystalline form of carbon in which each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement. This structure results in very strong bonds, making diamond the hardest naturally occurring substance known. Diamond is also an excellent thermal conductor and has a high refractive index, which contributes to its sparkle as a gemstone.

Graphite, on the other hand, is a soft, slippery form of carbon in which each carbon atom is covalently bonded to three other carbon atoms, forming hexagonal layers. These layers are held together by weak van der Waals forces, which allow the layers to slide past each other easily. This property makes graphite an effective lubricant and a good conductor of electricity.

It is worth mentioning that amorphous charcoal and coke, mentioned in Option B, are also forms of carbon, but they are not considered true allotropes because they do not have well-defined crystal structures like diamond and graphite.

Correct Answer: C. kerosine

Correct Answer: D. Aluminum

Explanation

Aluminum is not hygroscopic. It does not have a strong affinity for water vapor and does not absorb moisture from the air.

Correct Answer: B. Sodium trioxonitrate (V)

Correct Answer: D. 2-chloro-2-methylbutane

Explanation

Straight-chain hydrocarbon molecules that contain only singly-bonded carbons are called alkanes.

When naming these molecules, the final syllable in their name is ane.

1. Find and name the longest continuous carbon chain.

2. Identify and name groups attached to this chain.

3. Number the chain consecutively, starting at the end nearest a substituent group.

4. Designate the location of each substituent group by an appropriate number and name.

Correct Answer: C. AgNO3

Correct Answer: C) 3 and 2

Explanation

Element P has an atomic number of 12 while element Q has an atomic number of 15. The atomic number of an element is the number of protons in the nucleus of an atom of that element. The combination of P and Q gave a compound with the formula P m Q n . To determine the values of m and n, we need to use the valency of each element. The valency of an element is its combining power with other atoms. For example, an element with a valency of 2 can combine with two atoms of another element. Element P is in Group 2 of the periodic table, which means it has a valency of 2. Element Q is in Group 5, so it has a valency of 3. To form a neutral compound, the total positive charge of P and the total negative charge of Q must balance each other out. One way to achieve this is for two atoms of P to combine with three atoms of Q, giving the formula P 2 Q 3 . Therefore, the correct answer is option B: 2 and 3. It is important to understand the concept of valency in chemistry as it determines how elements react with each other to form compounds. For more information, please see the relevant sections of the recommended textbooks.

Correct Answer: D. Chromium and nickel

Correct Answer: A. 28.0%