Identify the elements with the following property and arrange them in the increasing order of their reactivity.
(a) An element that is a soft and reactive metal
(b) The metal that is an important constituent of limestone
(c) The metal that exists in the liquid state at room temperature

Important Questions on Periodic Classification Of Elements

MEDIUM

10th CBSE

IMPORTANT

Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5C>Q 5

Write the formula of the product formed when element A (atomic number 19) combines with element B (atomic number 17). Draw its electronic dot structure. What is the nature of the bond formed?

HARD

10th CBSE

IMPORTANT

Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5C>Q 1

On the basis of Mendeleev's periodic table given below, answer the questions that follow the table:

Question Image
(a) Name the elements that is in
(i) 1st group and 3rd period
(ii) VIIth group and 2nd period
(b) Suggest the formula for the following:
(i) oxide of nitrogen (ii) hydride of oxygen
(c) In group VIII of the periodic table, why does cobalt with atomic mass 58.93 appear before nickel having atomic mass 58.71?
(d) Besides gallium, which other two elements have since been discovered for which Mendeleev had left gaps in his periodic table?

(e) Using atomic masses of Li, Na and K, find the average masses of Li and K and compare it with the atomic mass of Na. State the conclusion drawn from this activity.