The photographic plate of film consists of a glass plate or thin strip of celluloid which is coated with the thin layer of an emulsion of silver bromide dispersed in gelatin.
133.
When $${\left( {N{H_4}} \right)_2}C{r_2}{O_7}$$ is heated, the gas evolved is
When ammonium dichromate is heated, it form nitrogen gas, $$C{r_2}{O_3}$$ and water.
\[{{\left( N{{H}_{4}} \right)}_{2}}C{{r}_{2}}{{O}_{7}}\xrightarrow{\Delta }C{{r}_{2}}{{O}_{3}}+4{{H}_{2}}O+{{N}_{2}}\]
134.
By pasing $${H_2}S$$ gas in acidified $$KMn{O_4}$$ solution, we get
135.
A violet compound of manganese $$(P)$$ decomposes on heating to liberate oxygen and compounds $$(Q)$$ and $$(R)$$ of manganese are formed. Compound $$(R)$$ reacts with $$KOH$$ in the presence of potassium nitrate to give compound $$(Q).$$ On heating compound $$(R)$$ with conc. $${H_2}S{O_4}$$ and $$NaCl,$$ chlorine gas is liberated and a compound $$(S)$$ of manganese along with other products is formed. Compounds $$P$$ to $$S$$ are
Lanthanides are the 14 elements of $${\text{III}}B$$ group and sixth period (at. no. = 58 to 71 ) that are filling $$4f$$ sub-shell of antipenultimate shell from 1 to 14. Actually, they are placed below the periodic table in horizontal row as lanthanide series.
137.
Composition of mischmetal is
A
5% of a lanthanoid metal, 95% of iron and traces of $$S, C, Ca$$ and $$Al$$
B
95% of an actinoid metal, 5% of iron and traces of $$S, C, Ca$$ and $$Al$$
C
95% of a lanthanoid metal, 5% of iron and traces of $$S, C, Ca$$ and $$Al$$
D
95% of a transition metal, 5% of iron and traces of $$S, C, Ca$$ and $$Al$$
Answer :
95% of a lanthanoid metal, 5% of iron and traces of $$S, C, Ca$$ and $$Al$$
In neutral or weakly alkaline medium thiosulphate is quantitatively oxidized by $$KMn{O_4}$$ to sulphate. According to this equation, $$8MnO_4^ - + 3{S_2}O_3^{2 - } + {H_2}O \to $$ $$8Mn{O_2} + 6SO_4^{2 - } + 2O{H^ - }$$
139.
hich of the following pairs has the same size?
In general, the atomic and ionic radii increases on moving down a group but the elements of second transition series $$(Zr, Nb, Mo)$$ have almost same radii as the elements of third transition series $$(Hf, Ta, W, etc).$$ This is because of lanthanoid contraction, i.e. imperfect shielding of one $$4f$$ $${e^ - }$$ by another.
140.
A red solid is insoluble in water. However it becomes soluble if some $$KI$$ is added to water. Heating the red solid in a test tube results in liberation of some violet coloured fumes and droplets of a metal appear on the cooler parts of the test tube. The red solid is
When $$KI$$ is added to mercuric iodide it disssolve in it and form complex.
\[\underset{\begin{smallmatrix}
\text{red, solid} \\
\text{(insoluble)}
\end{smallmatrix}}{\mathop{Hg{{I}_{2}}}}\,+KI\to \underset{\text{(soluble)}}{\mathop{{{K}_{2}}\left[ Hg{{I}_{4}} \right]}}\,\]
On heating $$Hg{I_2}$$ decomposes as
$$Hg{I_2} \rightleftharpoons Hg + \mathop {{I_2}}\limits_{{\text{(violet vapours)}}} $$