The elements 4 Be , _ 12 Mg and _ 20 Ca, each having two valence … - Vidyadip

Question

The elements $4 Be ,{ }_{12} Mg$ and ${ }_{20} Ca$, each having two valence electrons in their valence shells, are in periods 2,3 and 4 respectively of the modern periodic table. Answer the following questions associated with these elements, giving reason in each case:
a. In which group should they be?
b. Which one of them is least reactive?
c. Which one of them has the largest atomic size?

✓

Answer

a. All three elements have valency 2 . Thus, they should be present in group 2 of the periodic table.
b. On going down a group in the periodic table, the reactivity of an element increases because of decrease in the effective nuclear charge and increase in the atomic size; this makes the removal of valence electrons easy. Thus, among the given elements, 4 Be is the least reactive element.
c. On going down a group in the periodic table, the atomic size of elements increases because of the addition of new shells. Thus, among the given elements, 20Ca has the largest atomic size.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "[3 Mark Questions]" from Periodic Classification of Elements→Periodic Classification of Elements — all question types→Science STD 10 question papers→CBSE Board STD 10 question papers→CBSE Board question paper generator→

Similar questions

A hard material X which is mined from the earth is used as a house hold fuel and also for the generation of electricity at Thermal Power Stations. A soft material Y is also used us a fuel in the form of candles. A gaseous material Z which occurs along with petroleum is increasingly being used as a fuel in running vehicles in its compressed form.

What are materials, X, Y and Z?
When materials X, Y and Z are burned separately:

When material burns by producing a yellow, luminous flame?
Which material ultimately burns without producing a flame?
Which material can burn in a gas stove by producing a blue flame?

What are isomers? Draw the structures of two isomers of butane, $C _4 H _{10}$. Why can't we have isomers of first three members of alkane series?

How will you connect three resistors of resistances $2Ω, 3Ω$ and $6Ω $ obtain a total n si stance of:

$4 Ω,$
$1Ω$

Write the name and the structural formula of the compound formed when ethanol is heated at 443 K with excess of conc. $\text{H}_{2}\text{SO}_{4}$ State the role of conc. $\text{H}_{2}\text{SO}_{4}$ in this reaction. Write chemical equation for the reaction.

List two differences between acquired traits and inherited traits by giving an example of each.

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

Define the terms:

mineral.
ore.
gangue.

An element ' $X$ ' belong to $3^{\text {rd }}$ period and group 13 of the Modern Periodic Table.

Determine the valence electrons and the valency of ‘X’.
Molecular formula of the compound formed when ‘X’ reacts with an element ‘Y’ (atomic number=8).
Write the name and formula of the compound formed when ‘X’ combines with chlorine.

State the meaning of functional group in a carbon compound. Write the functional group present in (i) ethanol and (ii) ethanol acid and also draw their structures.

What are the three types of methods used for birth control (or regulating child birth)? Give one example of each type.