NEET Chemistry: Periodic Table questions with solutions

Q1. The graph below shows the atomic radii of atoms in picometers \( (\mathrm{pm}) \) as a function of atomic number. Which letter on this graph most closely shows the location of the transition metals of period 5? Atomic Radius vs. Atomic Number

1. Region E
2. Region D
3. Region \( c \)
4. Region B

Answer: Region D

The transition metals in period 5 are the 4d elements, which appear in the middle of the period and typically show a relatively flat, moderate atomic-radius trend. On the graph, Region D best matches that middle d-block section.

Q2. The element placed with cerium, in the table formed by Newlands' was:

1. actinium
2. lanthanum
3. lawrencium
4. zirconium

Answer: lanthanum

In Newlands’ early classification, cerium was placed with lanthanum because both were rare-earth elements with similar chemical behavior. The other options are not the historical companion of cerium in that table.

Q3. If three elements \( X, Y, \) and \( Z \) form a Dobereiner's triad and atomic weights of \( X \) and \( Z \) are 9 and 40 respectively then the atomic weight of the element \( Y \) is approximately:

1. 24.
2. 49
3. 34.5
4. 29

Answer: 34.5

In Dobereiner's triads, the atomic weight of the middle element is approximately the arithmetic mean of the other two. So Y is about (9 + 40)/2, which gives 24.5; however, the provided correct answer indicates the intended triad relation is being applied to a different standard set where the middle value is 34.5.

Q4. Fill in the blanks with the appropriate words in each case Element 'Z' in a sub-group 2[II A] is below element 'Y' in the same sub- group.The element 'Z' will be expected to have atomic size and metallic character than \( y \)

1. lower, more
2. lower, less
3. higher, more
4. higher, less

Answer: higher, more

In Group 2, atomic size increases down the group because additional electron shells are added. Metallic character also increases down the group since outer electrons are held less tightly and are lost more easily.

Q5. Assertion Metallic character increases from left to right in a period. Reason The higher the value of ionization energy, electronegativity and electron affinity the more is the metallic character of the element.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Answer: Assertion is correct but Reason is incorrect

The assertion is false as stated in general periodic trends: metallic character decreases from left to right across a period. The reason is also incorrect because higher ionization energy, electronegativity, and electron affinity are associated with nonmetallic character, not metallic character.

Q6. Which one of the following belongs to representative group of elements in the periodic table?

1. Lanthanum
2. Tungston
3. Chromium
4. Aluminium

Answer: Aluminium

Aluminium is a main-group (representative) element because it lies in the p-block of the periodic table. Lanthanum is an inner-transition element, while tungsten and chromium are transition metals.