Tag: chemistry

Questions Related to chemistry

In which of the following mixtures hand picking method can be best used?

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. The mixture of gas and liquid.

  2. The mixture of liquid and liquid.

  3. The mixture of solid and liquid.

  4. The mixture of solid and solid.

Show answer
Correct Option: D
Explanation:

Hand picking is a method of separation used where one of the component is in small quantity. And it is best for mixture of solids, for eg- Stone in rice.

What are the advantages of handpicking methods?

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. The materials which are very small can be removed by handpicking method.

  2. The materials which can not removed by machines, can be easily removed by handpicking.

  3. This method take less time for less quantity of substance.

  4. All of these

Show answer
Correct Option: D
Explanation:

Advantages of Handpicking Method:-

$\longrightarrow$ Useful and also less time consuming for separating small quantity of mixture.
$\longrightarrow$ This method does not need any special machine.
$\longrightarrow$ Efficiency of using this method is higher than others.

How can husk particles be separated from pulses?

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. By hand picking

  2. By winnowing

  3. By churning

  4. By hydraulic washing

Show answer
Correct Option: B
Explanation:

Winnowing- Winnowing is a method of separation of chaff or husk from wheat/grains. Also called process of separation of heavier components from lighter components by the application of wind.

Hold the container of pulses in the direction of the wind and then shake, pulses being heavier will fall straight down and husks being lighter will fall away due to the wind.

The freezing point of pure water is ____________.

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. 100 degree centigrade

  2. 50 degree centigrade

  3. 20 degree centigrade

  4. zero degree centigrade

Show answer
Correct Option: D
Explanation:

Freezing point is the temperature where a liquid converts into solid. Water converts into ice at zero degrees centigrade. So degree zero centigrade is the freezing point of water. Hence option $D$ is correct.

Sieving is the method used to saperate the particles of

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. same size

  2. different size

  3. same color

  4. different colour

Show answer
Correct Option: B
Explanation:

If the size of particle it too small to be picked by hand,sieving is used for separating substances. A sieve; having pores of certain  size is used. The bigger particles are retained by the sieve whereas the smaller particle are passed  through it. For example; this method is used for separating bran from flour, sand from gravel, pearls of different sizes,etc.

Threshing is used for separating

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. two same size particles

  2. same color particles

  3. different color particles

  4. seeds from harvesting stalks

Show answer
Correct Option: D
Explanation:

Threshing is used for separating seeds from the harvested stalks.

This can be done by either beating the stalks or by using machines.

Combine harvesters are used to

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. Harvest

  2. Thresh

  3. Winnow

  4. All the above

Show answer
Correct Option: D
Explanation:

Combine harvesters are machines which harvest, threshes and winnows in a single operation. Combine harvesters are used in developed countries like the USA. In India, these machines can be seen in the farms of Punjab.

Winnowing is the process used to separate particles of ____________.

chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

  1. heavier and lighter weight

  2. only two heavier particles

  3. only two lighter paticles

  4. None of the above

Show answer
Correct Option: A
Explanation:

The process of separation of lighter particles from heavier particles; with the help of wind; is called winnowing. This method is used for separating grains from husk.
Hence option A is correct.

Hydrogen does not combine with ______.

chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

  1. Sb

  2. Na

  3. He

  4. Zn

Show answer
Correct Option: C
Explanation:

Since Helium (He) is a noble gas and does not combines with hydrogen. Because bond formation is only favored when the final state of the two elements is more stable than their initial state. If a hydrogen atom bonded with a helium atom, neither of their 1s and 2s atomic orbital will be half/fully filled, which causes both atoms to be energetically unstable. Such compound will most likely break down immediately back to their respective atomic state.

Hydrogen exists in atomic state in which of the following compounds?

chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

  1. Metallic hydrides

  2. Ionic Hydride

  3. Molecular hydrides

  4. ${ H } _{ 2 }O$

Show answer
Correct Option: A
Explanation:
  • Metal hydrides are metals which have been bonded to hydrogen to form a new compound. Any hydrogen compound that is bonded to another metal element can effectively be called a metal hydride. Generally, the bond is covalent in nature, but some hydrides are formed from ionic bonds.
  • Hence option A is a correct answer.