Tag: chemistry

Questions Related to chemistry

The material used in photoelectric cells contains:

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $Cs$

  2. $Si$

  3. $Sn$

  4. $Ti$

Show answer
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 :

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. chloroform

  2. cyclohexane

  3. diispropyl ether

  4. diethylamine

Show answer
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.

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  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

Show answer
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?

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. Nickel-chrome alloy

  2. Barium sulphide

  3. Silver-plated metal

  4. None of these

Show answer
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:

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. lead carbonate

  2. basic lead carbonate

  3. barium carbonate

  4. strontium carbonate

Show answer
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.

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  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

Show answer
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:

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. sulphur

  2. sodium

  3. strontium

  4. magnesium

Show answer
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.

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. Haemoglobin

  2. Casein

  3. Keratin

  4. Interferon

Show answer
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?

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $CCl _4$

  2. $CH _2Cl _2$

  3. $CH _3 -CH _3$

  4. none of the above

Show answer
Correct Option: D

The uses of bleaching powder are:

chemistry substances in common use common salt some useful compounds in everyday life salts and their properties study of some important salts salts used in daily life

  1. it is used for bleaching cotton

  2. it is used as an oxidizing agent in chemical industries

  3. it can be used for disinfecting water

  4. all of the above

Show answer
Correct Option: D
Explanation:

Bleaching powder $(CaOCl _2)$ has many uses and some of them are as follows :-

1.It is used in bleaching dirty clothes in launder, as a bleaching agent in cotton and linen in the textile industry.
2.Due to evolution of nascent oxygen, it is used as an oxidizing agent in the chemical industries.
3.It can be used as a disinfectant which can be used for disinfecting water to make it potable.
Hence, the correct answer is option (D).