Tag: the s-block elements (alkali and alkaline earth metals)

Questions Related to the s-block elements (alkali and alkaline earth metals)

$MCrO _{4(s)}\overset{CH _{3}COOH(aq)}{\rightarrow}MCrO _{4}$  ( Suspension) above change is correct for which metal ion (s) ? 

  1. $Ba^{2+},Sr^{2+},Ca^{2+}$

  2. $Ba^{2+},Sr^{2+}$

  3. Only $Ba^{2+}$

  4. $Sr^{2+},Ca^{2+}$


Correct Option: C

Which is the major constituent of gun powder?

  1. Nitre

  2. Sulphur

  3. Charocal

  4. Chile salt petre


Correct Option: A
Explanation:

Gunpowder is a mixture of sulphur, charcoal and potassium nitrate (nitre). Among these Potassium Nitrate (saltpeter) is major constituent of gun powder.

The common name, "cream of tartar" refers to :

  1. $KHC _{4}H _{4}O _{6}$

  2. $K(SbO)C _{4}H _{4}O _{6}$

  3. $KNaC _{4}H _{4}O _{6}$

  4. $Mg _{2} (OH) _{2}(C _{4}H _{4}O _{6})H _{2}O$


Correct Option: A
Explanation:

Cream of tartar : Potassium bitartrate(potassium hydrogen tartrate) $KHC _4H _4O _6$

$Sr^{2+}$ forms a very unstable complex with $NO _{3-}$. A solution that was $0.001 M - Sr(ClO _{4}) _{2}$ and $0.05 M - KNO _{3}$ was found to have only $75$% of its strontium in the uncomplexed $Sr^{2+}$ form, the balance being $Sr(NO _{3})^{+}$. What is $K _{f}$ for complexation?

  1. $6.67$

  2. $0.15$

  3. $60$

  4. $26.67$


Correct Option: A

Potash alum is represented by the formula :

  1. $K _2SO _4\cdot Al _2(SO _4) _3\cdot 24H _2O$

  2. $K\cdot Al(SO _4) _2\cdot 12 H _2O$

  3. Both (a) and (b)

  4. None of these


Correct Option: B
Explanation:

Potassium alum or potassium aluminium sulphate is a chemical compound with a chemical formula $KAl(SO _4) _2$ and it is commonly found in its dodecahydrate form as $KAl(SO _4) _2.12H _2O$. 


Alum is the common name for this chemical compound.

$KO _2$ (potassium superoxide) is used in oxygen cylinders in space and submarines because, it : 

  1. decomposes to give oxygen

  2. eliminates moisture

  3. absorbs $CO _2$

  4. produces ozone


Correct Option: A,C
Explanation:

$KO _2$ on decomposition give oxygen and pottassium carbonate.The oxygen is used in oxygen cylinders in space and submarines
$2CO _2+4KO _2\rightarrow 3O _2+2K _2CO _3$.
Hence option A is correct.

In the reaction : $K _4[Fe(CN) _6] + K _2CO _3\rightarrow $ the product formed is :

  1. $FeCO _3$

  2. $KCN$

  3. $KFeCO _3$

  4. $K _3 [Fe(CN) _6]$


Correct Option: B
Explanation:

$K _4Fe(CN) _6+K _2CO _3\rightarrow 5KCN+KCNO+Fe+CO _2$.

In the above reaction only KCN is formed.

Hence, option B is correct.

${K} _{2}C{S} _{3}$ can be called potassium :

  1. Sulphocyanide

  2. Thiocarbide

  3. Thiocarbonate

  4. Thiocyanate


Correct Option: C

The material used in photoelectric cells contains:

  1. $Cs$

  2. $Si$

  3. $Sn$

  4. $Ti$


Correct Option: A,D
Explanation:

$Cs$ and $Ti$ is used in photoelectric cells because of low ionization enthalpy. electrons could be emitted very easily when exposed to light.

Metallic sodium is used as a drying agent for :

  1. chloroform

  2. cyclohexane

  3. diispropyl ether

  4. diethylamine


Correct Option: B,C
Explanation:

A. Chloroform - calcium chloride,phosphorous pentoxide are used as drying agent.
B. Cyclohexane - sodium,lithium aluminium hydride.
C. Diisopropyl ether - calcium chloride,sodium
D. Diethlyamine - simple distillation.