Explore topic-wise InterviewSolutions in Current Affairs.

Port city mentioned in ‘Periplus’ of Erythrean sea Machilipatnam (Mosalia)

The staff of factories was called Factors.

(b) they wanted to store goods bought at low prices

1. True

2. False

3. True

4. False

5. False

6. False

7. True

8. True

Methane is the simplest organic compound.

Students can use the following points as references.

• India’s maritime history began during the 3rd millennium B.C.E.
• When Indus valley had trade contact with Mesopotamia.
• Strabo mentions Rome and Greece had maritime trade relations with India.
• The Portuguese were the first Europeans to reach India by sea and traded in spices etc. followed by the Dutch.
• The shipbuilding activities of Chhatrapati Shivaji Maharaj are particularly noteworthy. Chhatrapati Shivaji Maharaj built a strong naval force.
• In the modern period, the British East India Company shipped substantial quantities of spices.
• Ship Building was a well-established craft.
• Some of the well-known shipyards in India today are Sembmarine Kakinada Ltd (SKL) India, Goa Shipyard Limited (GSL) India, Western India Shipyard Ltd.

The company formed by several Dutch companies United East India.

The East India company

(c) the expenditure for its maintenance exceeded the income earned from it

(a) Diamond

(b) Graphite

(c) Fullerenes

Diamond and graphite are the crystalline forms of carbon.

Receptors are embedded in the cell membranes.

Correct option: (b) Machilipatnam

St. Francis Church:

• Built-in 1503 as one of the oldest European churches in India.
• Originally known as St. Bartholomew.
• Constructed of wood and stone.
• First Portuguese church in India.
• Founded by Pedro Alvarez De Cabral.
• Built-in Persian architecture style.
• The Portuguese built a fort and within the fort, they built a church.
• History has it that Vasco da Gama died during his third visit to India and was buried here in 1524.
• After 14 years his body was moved to Lisbon.

(d) this encouraged merchants and artisans to come and settle down in Mumbai

The Dutch government issued a license to the company to conduct trading with the eastern countries. The same license permitted them to appoint staff, establish factories, build forts, engage in battles against the eastern countries, and also sign treaties with them. Accordingly, the company appointed a Governor-General to take care of Indian affairs.

(a) Crystals

(b) allotropy

(c) catenation

i) Diamond 

ii) graphite

Analgesics: The chemical substances which are used to relieve pain.

They are of two types:

(i) Narcotics

(ii) Non-narcotics

Non-narcotic drugs are effective in relieving skeletal pain, preventing heart attack, viral inflammation, etc.

Narcotic drugs are recommended for the relief in postoperative pain, cardiac pain and terminal cancer.

Correct option: (b) St. George

A crystalline form of carbon is sugar.

(a) The elements with atomic number 15, 16, 17 and 18 are non-metals in 3 period because silicon with atomic number 14 is metalloid and rest of the elements are metals in 3 period. 

(b) We know that non-metals form negative ions. So, the elements with atomic number 15, 16, 17 and 18 are the elements in 3 period which form negative ions.

(c) We know that metals have highest melting point due to strong metallic bond. So, the elements with atomic number 11, 12 and 13 have highest melting point in 3 period. 

(d) We know that metals form positive ions. So, the elements with atomic number 11, 12 and 13 are the elements in 3 period which form positive ions. 

(e) The elements with atomic number 11, 12 and 13 are the metals in 3 period. 

(f) We know that non-metals have low boiling point. So, the elements with atomic number 15, 16, 17 and 18 are the elements which have low boiling point.

Br has larger atomic size than Cl because the atomic size increases from top to bottom in a group. From top to bottom in a group, the number of shells increases. So, the atomic size increases.

All elements in same group shows same valence electrons and same chemical properties.

Fluorine atomic number 9 = 2, 7 

Chlorine atomic number 17 = 2, 8, 7 

Both of them show 7 valence electron.

All the elements in same period show same number of shells e.g., all elements in period 3, show 3 electron shells each.

(i) Physical properties of elements are a periodic function of their atomic masses.

(ii) The similar formula of oxides and hydrides formed by elements of the same group was selected as chemical property as basis of classification. The atomic number of hydrogen is 1 and hence it should occupy the first position in group 1 of the periodic table. But because of its chemical similarity with elements of group 1 and 17, the position of hydrogen in the periodic is not fixed.

The radius of an atom, i.e., the distance between the centre of the nucleus and the outermost shell of an atom is called atomic size. 

The atomic radius is measured in picometre. (1 pm = 10^–12 m)

(a) According to Mendeleev’s periodic law: The properties of elements are a periodic function of their atomic masses. It was the discovery of atomic number which led to a change in Mendeleev’s periodic law which was based on atomic mass.

(b) The noble gases are placed in a separate group because they are chemically very inert or unreactive (having completely filled outermost electron shells).

(a) Merits of Mendeleev’s classification of elements:

(i) Mendeleev’s periodic law predicted the existence of some elements that had not been discovered at that time.

(ii) Mendeleev’s periodic table could predict the properties of several elements on the basis of their positions in the periodic table.

(iii) It could accommodate noble gases when they were discovered.

(b) Anomalies of Mendeleev’s classification of elements:

(i) The position of isotopes could not be explained: If the elements are arranged according to atomic masses, the isotopes should be placed in different groups of the periodic table. But, the isotopes were not given separate places in Mendeleev’s periodic table. They were placed at the same place in the table. This placing of the isotopes at same place could not be explained by Mendeleev’s periodic law.

(ii) Wrong order of atomic masses of some elements could not be explained: In Mendeleev’s periodic table, when certain elements were put in their correct group on the basis of their chemical properties, it was found that the element with higher atomic mass comes first and the element with lower atomic mass comes later. Mendeleev’s periodic law could not explain this abnormal situation of wrong order of atomic masses.

Correct option  (C)

Explanation: 

Ne : 2, 8  Si :2,8,4 Mg : 2,8, 2 C : 2,4

Correct option  (C) X₂SO₄ and XCI 

Explanation: 

There is a big difference in lE₁ and lE₂ which means the element can form only unipositive ion i.e., X⁺ easily.

∴ The formula of sulphate of X is X₂SO₄ and that of chloride of X is XCl.

Merits of Mendeleev’s Periodic Table are: 

(i) Mendeleev left some gaps in his table. Predicted the chemical properties of these 3 elements which were discovered later and had same properties as predicted by Mendeleev, they were gallium, germanium and scandium. 

(ii) He arranged the elements very systematically in periods and groups.

Correct option  (D) I, III and IV only

Explanation: 

D is silicon which is a metalloid.

Reactivity of metals depends on the tendency to lose electrons. If the atomic size increases, the valence electrons are easily removed thereby forming positive ion. In case of metals the atomic size increases as we move down the table. Reactivity of non-metals depends on the tendency to gain electrons. As we move down the group, the tendency to gain electrons decreases because the atomic size increases, the nuclear force decreases.

An element with atomic number will form a basic oxide 11.

Lithium, sodium and potassium have same valence electron i.e. 1, hence they belong to same group. The group is called alkali metals group because all these elements form oxides which dissolve in water to form alkali.

‘n’stands for energy leve

Sodium and lithium belong to group IA or the periodic table.

Magnesium and calcium belong to group IIA of the periodic table.

(i) d.

(ii)c.

(iii) e.

(iv) Covalent bond .

(v) Ionic bond .

The atomic size in a period decreases as we move from left to right.

B, C, N does not belong to a group.

(D) The valency of ₁₀Ne = 2, 8 is 0.

(A) The same number of protons is  ⁵⁴₂₇X.

The reflecting surface of convex and concave mirror is considered to form a part of the surface of a sphere. So they are called spherical mirrors.

Those mirrors are :