1. UNESCO inaugurated the celebration of 2019 as the International Year of the Periodic Table of Chemical Elements to celebrate its completion of how many years?
(a) 100
(b) 150
(c) 75
(d) 50
(e) None of the above/More than one of the above
[65th B.P.S.C. (Pre) 2019]
Ans. (b) 150
- In 2019, UNESCO launched a year-long celebration to commemorate the completion of 150 years since the creation of the Periodic Table of Chemical Elements by Russian scientist Dmitri Ivanovich Mendeleev in 1869.
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2. Assertion (A): In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group. Reason (R): In a group, the atomic radii generally increase from top to bottom.
(a) Both (A) and (R) are individually true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are individually true, but R is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
[I.A.S. (Pre) 2003]
Ans. (d) (A) is false but (R) is true
- As you move down a certain group in the periodic table of elements, the electron affinity gets weaker, but it gets stronger as you go up the group and from left to right across periods.
- Atoms get bigger as the number of electron shells increases, so the radius of atoms increases when you go down a group.
- On the other hand, the size of atoms will decrease when you move from left to right of a certain period.
- Therefore, the assertion is not true while the reason is correct.
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3. Consider the following statements with reference to the periodic table of chemical elements :
1. Ionization potential gradually decreases along a period
2. In a group of elements, electron affinity decreases as the atomic weight increases
3. In a given period, electronegativity decreases as the atomic number increases
Which of these statement (s) is/are correct?
(a) 1 only
(b) 2 only
(c) 1 and 3
(d) 2 and 3
[I.A.S. (Pre) 2001]
Ans. (b) 2 only
- Going from left to right across a row on the periodic table, the atomic radius gets smaller and the ionization energy increases.
- As you go down a group, the ionization energy decreases.
- As you go up a group, the electron affinity decreases and the atomic weight increases.
- As you move from left to right, the electronegativity increases because the atom gets a stronger pull from the nucleus.
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4. What is the usual property of oxides of Groups 3 and 4?
(a) Basic and Acidic
(b) Basic
(c) Acidic
(d) Neutral
[43rd B.P.S.C. (Pre) 1999]
Ans. (a) Basic and Acidic
- The elements in Groups 3 and 4 of the periodic table typically react as either an acid or a base.
- These elements can react in either way.
- They are called amphoteric.
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5. The element found maximum in the soil layer is –
(a) Oxygen
(b) Nitrogen
(c) Manganese
(d) Silicon
[42nd B.P.S.C. (Pre) 1997]
Ans. (a) Oxygen
- The element found the maximum in the soil layer is Oxygen at 46.60% followed by Silicon at 27.72%, Aluminium at 8.13%, Iron at 5.00%, and Calcium at 3.65%.
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6. Which one of the following is present in the largest amount in terms of percent by mass in the earth’s crust?
(a) Silicon
(b) Oxygen
(c) Carbon
(d) Calcium
[I.A.S. (Pre) 1997]
Ans. (b) Oxygen
- The element found the maximum in the soil layer is Oxygen at 46.60% followed by Silicon at 27.72%, Aluminium at 8.13%, Iron at 5.00%, and Calcium at 3.65%.
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7. Which is the most abundant element after Oxygen?
(a) Silicon
(b) Carbon
(c) Sodium
(d) Chlorine
[M.P.P.C.S. (Pre) 2005]
Ans. (a) Silicon
- After Oxygen, the element that is most present on earth’s surface is Silicon.
- It was found by J.J. Berzelius in 1824 and the name ‘Silicon’ came from the Latin word silex.
- Silicon is used to make semiconductors for computers.
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8. Which of the following is the most common element in the Universe?
(a) Hydrogen
(b) Oxygen
(c) Nitrogen
(d) Carbon
[U.P.P.C.S. (Pre) 2007]
Ans. (a) Hydrogen
- Hydrogen is the most common element in the Universe, making up around 75% of all matter.
- Helium takes up the other 25%.
- Oxygen is the most abundant element in the Earth’s crust, accounting for about 46.6%.
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9. Approximately how many different chemical elements exist on the earth?
(a) 300
(b) 250
(c) 200
(d) 100
[R.A.S./R.T.S. (Pre) 2003]
Ans. (d) 100
- A chemical element is a type of material made of atoms that have the same number of protons in their centers.
- So far, 118 elements have been found, including a new one called ‘Ununseptium’ (Tennessine) that was discovered in 2010.
- Ununseptium is a made-up element with the number 117.
- In 2003, there were around 100 known elements.
- Therefore, option (d) is correct.
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10. Which of the following is a fundamental element :
(a) Sand
(b) Diamond
(c) Marble
(d) Sugar
[U.P.P.C.S. (Pre) 1995]
Ans. (b) Diamond
- Diamonds are made up of pure carbon and are a basic element.
- Sand is made of silicon and oxygen.
- Marble is composed of calcium, carbon, and oxygen.
- Sugar is made of carbon, hydrogen, and oxygen.
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11. The chemical composition of a diamond is?
(a) Carbon
(b) Nitrogen
(c) Nickel
(d) Zinc
[Uttarakhand P.C.S. (Pre) 2007]
Ans. (a) Carbon
- Diamond is the purest form of Carbon, so it is a basic element.
- Sand is made of Silicon and Oxygen.
- Marble is made of Calcium, Carbon, and Oxygen.
- Sugar is mainly made of Carbon, Hydrogen, and Oxygen.
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12. Which of the following is not a type of element?
(a) Metals
(b) Nonmetals
(c) Gases
(d) Metalloids
(e) None of the above/More than one of the above
[65th B.P.S.C. (Pre) 2019]
Ans. (c) Gases
- The elements of the periodic table can be classified as metals, metalloids, and nonmetals.
- Hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, and radon are all elements and are nonmetals.
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13. Which of the following elements was first produced artificially?
(a) Neptunium
(b) Plutonium
(c) Francium
(d) Technetium
[Jharkhand P.C.S. (Pre) 2013]
Ans. (d) Technetium
- Technetium is a kind of chemical and it was the first element ever made by humans.
- It was discovered in 1937 by Carlo Perrier and Emilio Segre.
- It has an atomic number of 43.
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