The s-Block Elements - Online Test
Q1. One of the following is the rarest of all alkaline earth metals
Answer : Option C
Explaination / Solution:
Ra is found in Uranium and thorium ores in trace amounts as small as a seventh of a gram per ton of uraninite so it is rarest of all alkaline earth metals
Q2. Among the alkali metals the most abundant are:
Answer : Option B
Explaination / Solution:
Na and K are highly abundant. Constituting 2.5 and 2.4 percent of the Earth's crust respectively the othwe alkali metals are considerably rare.
Q3. The general electronic configuration of alkali metals is
Answer : Option D
Explaination / Solution:
The general electronic configuration of alkali metals is ns1 as their outer most electron enters the S orbital and they have only on electon in their velence shell.
Q4.
The general electronic configuration of ns2 exit in:
Answer : Option A
Explaination / Solution:
The general electronic configuration of ns2 exists in alkaline earth metals as their outer most electron enter the S orbital and they have only two electrons in their valence shell
Q5. The alkali metals and their salts impart characteristic colour to an oxidizing flame because:
Answer : Option C
Explaination / Solution:
Alkali metals have one unpaired electron in their valence shell which gets excited by absorbing the energy from flame, excited states are very unstable and quickly move back to lower state ,at that time they emit the energy in the form of radiation in visible reason of electromagnetic spectrum and is abserved as characteristic colour.
Q6. Flame photometry is used to determine the concentration of the
Answer : Option D
Explaination / Solution:
Flame photometry is used to determine the concentration of alkali metalions, alkaline earth metals are quite sensitive to flame photometry.
Q7. The electronic configuration of Rn7s1 belongs to
Answer : Option D
Explaination / Solution:
Francium will fill orbitals all the way up to 7S (7th period) subshell whrer it will have half filled orbital : 7S1 .
Q8. The alkali metals burn vigorously in oxygen forming oxides. Hence, potassium forms
Answer : Option A
Explaination / Solution:
alkali metals burns vigorously to form superoxides. Superoxide O2- ion is only in the presence of large cations such as potassium, Rb and Cs
Q9. What is the oxidation state of K in
Answer : Option C
Explaination / Solution:
K has +1 oxidation state. "The potassium atom losses one electron when forming compound as it has one electron on it's valence shell".
Q10.
What is M?
Answer : Option B
Explaination / Solution:
M is alkali metal. Alkali metals reacts with water vigorously to form hydroxide (OH-) and dihydrogen (H2)
