CBSE Class 10 Science 2017 · Paper 31(B)/C · Question 10
An element (atomic number 11) burns in the presence of air to form an oxide.
- (a)Identify the element and write its electronic configuration.
- (b)What is the group number and period number of this element ?
- (c)Write the name and the formula of the compound formed when this oxide dissolves in water.
Answer
The element is sodium (), in group 1 and period 3; its oxide dissolves in water to form sodium hydroxide, .
(a) The element is sodium, Na. Its electronic configuration is 2, 8, 1 (K 2, L 8, M 1).
(b) Group number 1; period number 3.
(c) The compound is sodium hydroxide, NaOH, formed when sodium oxide dissolves in water: .
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