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Uses of alkali and alkaline earth metals - class-XI

Description: uses of alkali and alkaline earth metals
Number of Questions: 17
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Tags: s-block elements chemistry the s-block elements elements of group 1 and group 2 the s-block elements (alkali and alkaline earth metals)
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$MCrO _{4(s)}\overset{CH _{3}COOH(aq)}{\rightarrow}MCrO _{4}$  ( 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.

Read the assertion and reason carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.


Assertion: Potassium and caesium are used in photoelectric cells.
Reason: Potassium and caesium emit electrons on exposure to light.

  1. If both assertion and reason are true and the reason is a correct explanation of the assertion

  2. If both assertion and reason are true but reason is not a correct explanation of the assertion

  3. If the assertion is true but reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but the reason is true


Correct Option: A
Explanation:

Potassium and Caesium are electropositive elements with very low ionisation potential so they emit electrons on exposure to light.


Hence assertion is correct and the reason is the true explanation for the assertion.

At night when the lights of a scooter or a car fall on a road-sign or on a vehicle moving ahead, the painted letters or numbers shine with a glow. Which of the following is a luminous paint?

  1. Nickel-chrome alloy

  2. Barium sulphide

  3. Silver-plated metal

  4. None of these


Correct Option: B
Explanation:
Barium sulphide can be employed as a short wavelength emitter for electronic displays and used in electronics, paint pigments, flame retardant, luminous paints, and producing pure hydrogen sulphide.

A metal salt solution forms a yellow precipitate with potassium chromate in acetic acid, a white precipitate with dilute sulphuric acid but does not give precipitate with sodium chloride or iodide. The white precipitate obtained when sodium carbonate is added to the metal salt solution will consist of:

  1. lead carbonate

  2. basic lead carbonate

  3. barium carbonate

  4. strontium carbonate


Correct Option: C
Explanation:

Pb and Ba both give yellow ppt with $K _2CrO _4$ in acetic and white precipitate with dil. $H _2SO _4$. but lead salts give a precipitate with sodium chloride or iodide also whereas barium does not. It means given salt is barium salts and with sodium carbonate, it gives a white precipitate of barium carbonate.

Beautiful colours of fireworks are produced by adding salts of various metals into the burning mixture. The firework colours of different metals are mentioned here. Pick the false one.

  1. Calcium gives a brick-red light

  2. Sodium gives a yellow light

  3. Copper gives a green light

  4. Strontium gives a blue light


Correct Option: D
Explanation:
The Magical Colors of Fireworks
  • Red-strontium salts, lithium salts.
  • Orange- calcium salts.
  • Gold-incandescence of iron (with carbon), charcoal, or lampblack.
  • Yellow-sodium compounds.
  • White-white-hot metal, such as magnesium or aluminum.
  • Green-barium compounds + chlorine producer,copper.
  • Blue-copper compounds + chlorine producer.
  • Brick-red light-Calcium

Hence option D is wrong option.

Sparkling red colour after the blast of fire crackers is due to the presence of:

  1. sulphur

  2. sodium

  3. strontium

  4. magnesium


Correct Option: C
Explanation:

Firework colors come from the use of metal salts, packed in pellets called “stars.”Metal salts commonly used in firework displays include: strontium carbonate (red fireworks), calcium chloride (orange fireworks), sodium nitrate (yellow fireworks), barium chloride (green fireworks) and copper chloride (blue fireworks). 

Hence,Sparkling red colour after the blast of fire crackers is due to the presence of Strontium.

Cancer is a disease where body cells grow unchecked. A protein found in the body interferes with the growth of cancer cells. It is used for the treatment of cancer. Identify it.

  1. Haemoglobin

  2. Casein

  3. Keratin

  4. Interferon


Correct Option: B
Explanation:

Casein is a slow-digesting dairy protein that people often take as a supplement. It releases amino acids slowly, so people often take it before bed to help with recovery and reduce muscle breakdown while they sleep. Several studies have shown it helps boost muscle growth, along with a ton of other benefits.

Also Casein interferes with the growth of cancer cells and hence is also used for the treatment of cancer.
Hence option B is correct answer.

Which of the following product is obtained when bleaching powder is distilled with acetone?

  1. $CCl _4$

  2. $CH _2Cl _2$

  3. $CH _3 -CH _3$

  4. none of the above


Correct Option: D
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