Tag: general introduction: importance and scope of chemistry

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Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

How many elements is expected in period number 10 of the periodic table?

  1. 68

  2. 72

  3. 50

  4. 32
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The number of elements in a period is determined by the number of orbitals being filled. For period n, the number of elements is given by 2 * (n+1)^2 / 4 or similar patterns; for period 10, the calculation leads to 72 elements based on the filling of 8s, 5g, 6f, 7d, and 8p orbitals.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Which of the following is an ionic compound?

  1. ${ SO } _{ 3 }$
  2. $ICl$
  3. $KI$
  4. ${ CHCl } _{ 3 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
An ionic compound is composed of cation and anion and by the electrostatic force of attraction. But after formation, cation attracts the electron pair towards itself and cause some deformation of electron density of anion. Above all if the ionic character predominates over covalent character, then we call it ionic.

$KI$ consist of $K^+ $ cations  and $I^-$ anions.

The bond is purely ionic and the compound is ionic.


Option C is correct.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

$0.14\ g$ of an element on combustion gives $0.28\ g$ of its oxide. That is that element?

  1. Nitrogen

  2. Carbon

  3. Fluorine

  4. Sulphur
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass of element = 0.14g, Mass of oxide = 0.28g. Mass of oxygen = 0.28 - 0.14 = 0.14g. Equivalent weight = (Mass of element / Mass of oxygen) * 8. Equivalent weight = (0.14 / 0.14) * 8 = 8. Sulphur has an equivalent weight of 8 (valency 2, atomic mass 32).

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Milk is a compound.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Milk is not compound. A compound is an entity consisting of two or more different atoms associating with chemical bonds. Milk is an emulsion or colloid of fat globules within a water-based fluid that contains dissolved carbohydrates and protein aggregates with minerals.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

What will be the product, if dilute hydrochloric acid is added to $FeS$?

  1. Element

  2. Mixture

  3. Compound

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

If you heat iron filings ans sulphur to a sufficiently high temperature you form iron sulphide 
$Fe + S \rightarrow FeS$
If you add HCl to this the following reaction occurs: 
$FeS + 2HCl \rightarrow FeCl _2 + H _2S$ 
$H _2S$ gas is given off and iron chloride is produced. 

Both are chemical compounds.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

What is formed if a mixture of powdered iron and sulphur is heated in a test tube?

  1. An element

  2. A mixture

  3. A compound

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

A mixture is made when you combine matter in a way where the components can be separated again. A compound results from a chemical reaction between components, forming a new substance. For example, you can combine iron filings with sulfur to form a mixture. All it takes is a magnet to separate the iron from the sulfur. On the other hand, if you heat the iron and sulfur, you form iron sulfide, which is a compound.
$Fe+S \rightarrow FeS$