NCERT Class 10 Chapter 4 Classification of Elements CBSE Board Sample Problems Very Short Answer
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Question
Which element was named as Eka-aluminium earlier?
Solution
Gallium
Question
According to which periodic law, every eight element repeat its property?
Solution
Newland’s Octave
Question
An element ‘X’ has mass number 35 and the number of neutrons is 18. Identify the group number and period of ‘X’
Solution
Mass Number= Protons + Neutrons
Number of protons =17, therefore Atomic number of ‘X’=l 7
Hence ‘X’ belongs to 3Id period and 1 7” group.
Question
How does valency vary across the period?
Solution
The valency first increases and then decreases to zero across the period.
Question
Out of Lithium and Potassium, which one has strong metallic character and why?
Solution
Potassium is more metallic as the metallic character increases down the group.
Question
What happens to the metallic character of elements as we move from left to right in a period?
Solution
It decrease from left to right in a period.
Question
Which period and group of the periodic table does an element with atomic number 4 belong to?
Solution
This element belongs to group 2 and period 2 of the periodic table.
Question
Why does Neon show extremely low reactivity?
Solution
Neon shows low reactivity because its outermost shell is completely filled.
Question
State Newlands’ law of octaves.
Solution
According to Newlands’ law of octaves when the elements are arranged in order of increasing atomic weights then every eighth element has properties similar to that of the first element.