Chemistry

Chemical Compounds and Reactions

505 Questions

Chemical compounds and reactions involve understanding the properties, colors, and formation of various chemical substances. Questions focus on identifying precipitates, observing color changes during reactions, and naming common compounds. This topic is a fundamental part of the chemistry syllabus for competitive exams.

identifying precipitateschemical reaction colorscompound namingcolloidal particle propertiesacid base reactions

Chemical Compounds and Reactions Questions

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.

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

Crystallisation is an example of ____________.

  1. physical change

  2. biological change

  3. chemical change

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

The process of formation of solid crystals from a homogeneous solution is called crystallization. It is a physical change. Crystallization is the solidification of atoms or molecules into a highly structured form called a crystal. It can also refer to the solid-liquid separation and purification technique in which mass transfer occurs from a liquid solution to a pure solid crystalline phase.

For example Salt we get from seawater can have many impurities in it. To remove these impurities, the process of crystallization is used.

Hence, the correct option is $A$

Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Methanol is called as Marine Methanol beacuse:

  1. it is an essential compound for marine life

  2. it is mostly obtained from deep sea bed

  3. it is used as a marine fuel

  4. it serves as a signal indicator for big ships on burning
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Currently, methanol is being developed and utilized as a marine fuel. Interest in methanol as a ship fuel is growing in response to international regulatory changes and cost advantages relative to other fuels. Methanol is an alternative which is sulphur free, has low emissions; perhaps three to four times cheaper than marine distillate fuel; and has a higher score on the International Martine Organization (IMO) energy efficiency design index (EEDI)than LNG or diesel. Globally, Methanol is already in widespread production (~70 million tons per annum) for a multitude of chemical and energy applications, and is one of the world’s most widely shipped chemicals.

Multiple choice chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

Compounds $A$ and $B$ are treated with dilute $HCl$ separately. The gases liberated are $Y$ and $Z$ respectively $Y$ turns acidified dichromate paper green while $Z$ turns lead acetate paper black. So $A$ and $B$ compounds are respectively:

  1. $Na _2SO _3, Na _2S$
  2. $NaCl, Na _2CO _3$
  3. $Na _2S, Na _2SO _3$
  4. $Na _2SO _3, K _2SO _4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Na2SO3 + HCl produces SO2 gas, which turns acidified dichromate paper green. Na2S + HCl produces H2S gas, which turns lead acetate paper black. Thus, A is Na2SO3 and B is Na2S.

Multiple choice chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

Which compound(s) is/are produced when hydrochloric acid is added to silver nitrate solution?

  1. ${ HNO } _{ 3 }$
  2. $AgCl$

  3. Both A and B

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

${ AgNO } _{ 3 }+HCl\rightarrow AgCl+{ HNO } _{ 3 }$

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Which of the following salt gives a crimson red colour in flame test?

  1. $BaCl _{2}$
  2. $CaCl _{2}$
  3. $BeCl _{2}$
  4. $SrCl _{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Strontium chloride($SrCl _2$) gives crimson red colour in the flame test. It is due to the excitation of electrons by the thermal energy, which is then followed by de-excitation of electron to ground state along with liberation of light in the visible range.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Which of the following does/do not impact characteristic colour to the flame?

  1. $MgSO _4$
  2. $CaCl _2$
  3. $Sr(NO _3) _2$
  4. $BeCl _2$
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

$CaCl _2$ has orange colour.
$Sr(NO _3) _2$ has crimson colour flame.


Be and Mg do not impart any colour to the flame due to higher ionization energy and small size.The energy of the flame is not sufficient to excite the electrons to higher energy levels. Hence, they do not impart any characteristic colour to the flame

Multiple choice evs look, learn and experience brief introduction to atoms of elements elements and atoms introduction of atom

We have four substances P,Q,R,S. Substance P is dark coloured violet solid having diatomic molecules. Solution of P in alcohol is an Antiseptic 'T' Substance 'Q'is a white solid usually recovered from sea on a large scale. Substance 'R' is also a white solid insoluble in water and used in the form of small balls for safe storage of woolen clothes. Substance 'S' is a white solid too used in dry cell. P,Q,R,S,T, may be -(choose correct option)

  1. P-lodine, Q-Napthalene,R-$\displaystyle R-NH _{4}CI$ S-Nacl, T-lodine tincture
  2. P-NaCl,Q-Napthalene, $\displaystyle R-NH _{4}CI$

    S-lodine, T-lodine tincture
  3. P-lodine tincture, Q-$\displaystyle R-NH _{4}CI$ R- lodine, S-Napthalene, T-NaCl
  4. P-lodine, Q-Nacl, R- Napthalene,

    S-$\displaystyle R-NH _{4}CI$, T-lodine tincture
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

P = lodine $\displaystyle 1 _{2}$, dark coloured  violet solid Q = NaCl, recovered  from sea on large scale. R = Nephathalene, used in the from of small balls for safe storage of woolen clothes S = $\displaystyle NH _{4}Cl$, used in dry cells
T = TIncture iodine, a solution of iodine in alcohol as antiseptic 

Multiple choice chemistry substances in common use percent composition water of crystallisation percentage composition and empirical formula

Copper sulphate pentahydrate is commonly called as____, whereas ferrous sulphate heptahydrate is commonly called as _____ .

  1. white vitriol, blue vitriol

  2. green vitriol, blue vitriol

  3. blue vitriol, green vitriol

  4. blue vitriol, white vitriol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Copper sulphate pentahydrate ($CuSO _4.5H _2O$) commonly known as blue vitrol contains 5 water molecules which gives it a blue color. Similarly, the green color of ferrous sulphate heptahydrate ($FeSO _4.7H _2O$) is due to 7 molecules water present in it. This water is responsible for the geometric shape and color of the crystals.

Multiple choice aluminium patterns and properties of metals chemistry

Which of the following compounds can make clothes fire proof ?

  1. $FeSO _{4}$
  2. $Al _{2}(SO _{4}) _{3}$
  3. $Cu _{2}SO _{4}$
  4. $MgSO _{4}.7H _{2}O$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Al _2(SO _4) _3$ used to make fire proof clothes.