Classification of Elements and Periodicity in Properties MCQ Questions & Answers in Inorganic Chemistry | Chemistry
Learn Classification of Elements and Periodicity in Properties MCQ questions & answers in Inorganic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
181.
An element has atomic number 79. Predict the group and period in which the element is placed.
A cation has always the lesser ionic size than a metal atom due to loss of electrons and an anion has always the greater size than metal atom due to gain of electrons. The given species are isoelectronic species as they contain same number of electrons.
For isoelectronic species ionic radii $$ \propto \frac{1}{{{\text{atomic number}}}}.$$
$$\eqalign{
& {\text{Ion}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,:C{a^{2 + }}\,\,\,\,{K^ + }\,\,\,\,Ar\,\,\,\,\,\,{S^2}\,\,\,Cl \cr
& {\text{Atomic}}\,\,{\text{number}}\,\,\,:\,20\,\,\,\,\,\,\,\,\,19\,\,\,\,\,\,\,\,18\,\,\,\,\,16\,\,\,\,\,\,\,\,17 \cr
& {\text{So, the correct order of size is as}} \cr
& C{a^{2 + }} < {K^ + } < Ar < C{l^ - } < {S^{2 - }} \cr} $$
183.
Among the following, the one which is most basic is
A
$$ZnO$$
B
$$MgO$$
C
$$A{l_2}{O_3}$$
D
$${N_2}{O_5}$$
Answer :
$$MgO$$
$$ZnO$$ and $$A{l_2}{O_3}$$ are amphoteric oxide, $${N_2}{O_5}$$ is oxide of non-metal, so it is acidic and hence, $$MgO$$ is most basic among $$A{l_2}{O_3},ZnO,{N_2}{O_5}$$ and $$MgO.$$
184.
Which is the correct order of second ionization potential of $$C, N, O$$ and $$F$$ in the following ?
A
$$O > N > F > C$$
B
$$O > F > N > C$$
C
$$F > O > N > C$$
D
$$C > N > O > F$$
Answer :
$$O > F > N > C$$
The second ionization potential means removal of electron from cation
$$\eqalign{
& {C^ + } = 1{s^2}2{s^2}2{p^1},{N^ + } = 1{s^2}2{s^2}2{p^2} \cr
& {O^ + } = 1{s^2}2{s^2}2{p^3},{F^ + } = 1{s^2}2{s^2}2{p^4} \cr} $$
Therefore $$O > F > N > C$$
185.
The ions $${O^{2 - }},{F^ - },N{a^ + },M{g^{2 + }}$$ and $$A{l^{3 + }}$$ are isoelectronic. Their ionic radii show
A
an increase from $${O^{2 - }}$$ to $${F^ - }$$ and then decrease from $$N{a^ + }$$ to $$A{l^{3 + }}$$
B
a decrease from $${O^{2 - }}$$ to $${F^ - }$$ and then increase from $$N{a^ + }$$ to $$A{l^{3 + }}$$
C
a significant increase from $${O^{2 - }}$$ to $$A{l^{3 + }}$$
D
a significant decrease from $${O^{2 - }}$$ to $$A{l^{3 + }}$$
Answer :
a significant decrease from $${O^{2 - }}$$ to $$A{l^{3 + }}$$
On increasing atomic number of isoelectronic species ionic radii decreases due to increasing effective nuclear charge $$\left( {{Z_{eff}}} \right).$$
$${\text{Radius}} \propto \frac{1}{{{\text{Atomic}}\,{\text{number}}}} \propto \frac{1}{{{Z_{eff}}}}$$
So, as the negative charge increases ionic radii increases while on increasing positive charge ionic radii decreases. Anions having higher ionic radii than the cation.
Hence, order of radii $${O^{2 - }} > {F^ - } > N{a^ + } > M{g^{2 + }} > \,\,\,A{l^{3 + }}$$
186.
An element having electronic configuration $$1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}$$ forms
A
Acidic oxide
B
Basic oxide
C
Amphoteric oxide
D
Neutral oxide
Answer :
Basic oxide
It is electronic configuration of alkali metal. Hence it will form basic oxide.
187.
Few general names are given along with their valence shell configurations. Mark the incorrect name.
A
$$n{s^2}n{p^6} $$ - Noble gases
B
$$n{s^2}n{p^5} $$ - Halogens
C
$$n{s^1} $$ - Alkali metals
D
$$n{s^2}n{p^2} $$ - Chalcogens
Answer :
$$n{s^2}n{p^2} $$ - Chalcogens
$$n{s^2}n{p^2}$$ are members of carbon family. Chalcogens is the general name of 16th group elements.
188.
The first periodic law stated by Mendeleev was
A
there is no correlation in the properties and atomic weights of the elements
B
the properties of the elements are a periodic function of their atomic numbers
C
the properties of the elements are a periodic function of their atomic weights
D
the properties of the elements are a periodic function of their empirical formula
Answer :
the properties of the elements are a periodic function of their atomic weights
No explanation is given for this question. Let's discuss the answer together.
189.
Which one of the following is the strongest base?
A
$$As{H_3}$$
B
$$N{H_3}$$
C
$$P{H_3}\,$$
D
$$Sb{H_3}$$
Answer :
$$N{H_3}$$
Nitrogen, being smallest in size, can give up its lone pair of electrons most easily.
190.
The elements in which electrons are progressively filled in $$4f$$ orbital are called
A
actinoids
B
transition elements
C
lanthanoids
D
halogens
Answer :
lanthanoids
In lanthanoids, electrons are progressively filled in $$4f$$ orbital.