Tag: chemistry

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Multiple choice chemistry changes around us crystallisation process of separating components of a mixture physical changes

Which of the following is not a feature of chemical change?


(I) Original substance can be obtained by simple physical methods.
(II) It is a temporary change.
(III) The new substances formed have properties different from those of the reacting substances.

  1. I, II

  2. I, III

  3. II, III

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One more new substances one formed in a chemical change. The new substances formed have properties different from those of the reacting substances. A chemical change is always accompanied by the absorption or evolution of energy in the form of heat, light or sound.

Multiple choice chemistry changes around us crystallisation process of separating components of a mixture physical changes

One of most common solvent used for crystallization is:

  1. syrup

  2. normal saline

  3. water

  4. sulphuric acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

One of the most common solvents is water. It is also called as a universal solvent.

Crystallization is the process of formation of crystals. Since water can be easily added or removed from the system. It is the most common for eg. ${ CuSO } _{ 4 }.5{ H } _{ 2 }O$
                                     ${ Fe } _{ 2 }{ O } _{ 3 }.n{ H } _{ 2 }O$

Multiple choice chemistry changes around us crystallisation process of separating components of a mixture physical changes

The process of obtaining salt by evaporation of seawater is known as :

  1. crystallisation

  2. sedimentation

  3. galvanization

  4. amalgamation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is known as crystallization - because salt is obtained in crystal form.

Sedimentation is depositing solid as sediment
Galvanization - is the process of protecting iron/metal by a coating of zinc.
Amalgamation - is the formation of amalgam (an alloy of mercury with another metal).

Multiple choice chemistry changes around us crystallisation process of separating components of a mixture physical changes

Crystals are formed by ions, atoms, and molecules having an internal pattern that is ___________ and ___________.

  1. irregular, non-repeating

  2. regular, repeating

  3. regular, non-repeating

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In crystalline solids, the atoms, ions or molecules are arranged in an ordered and symmetrical pattern that is repeated over the entire crystal. The smallest repeating structure of a solid is called a unit cell, which is periodically repeated in three dimensions on a lattice.

Multiple choice chemistry changes around us crystallisation process of separating components of a mixture physical changes

Which of the following is the most common solvent used for crystallization?

  1. Organic solvent benzene

  2. Plain water

  3. A salt solution of water

  4. Dilute solution of sulphuric acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The most common solvent used in crystallization is water, it does not dissolve the substance to be purified at room temperature, but it dissolves it well at solvent's boiling point, and dissolves soluble impurities well at room temperature.
Water is capable of dissolving a variety of different substances than any other liquid and is called the universal solvent.