Explore topic-wise InterviewSolutions in Current Affairs.

(i) Na has similar properties as of the same group members as K, Rb, Cs. They contain 1 valence in the outermost shell so all of them are reactive.

(ii) Nitrogen:- 2,5

Phosphorus:- 2,8,5

Electronegativity is a measure of how strongly atoms attract bonding electrons to themselves.

Nitrogen is more electronegative because in nitrogen outermost shell is nearer to nucleus and nucleus will attract electrons easily.

(a) Lead chloride

(b) Silver chloride

(c) Barium sulphate and lead sulphate

(d) Basic lead chloride

(e) Sodium hydrogen sulphate

(f) Sodium potassium carbonate

(g) Sodium argentocyanide

(h) Potash alum

(i) Potassium bromide and potassium chloride

(j) Calcium sulphate

(a) (i) F and Cl  (ii) Na and K. 

(b) Newland’s law of octaves.

N(7) it show similar chemical properties.

• The arrangement of these elements is known as Dobereiner & triad.
•   Example, Lithium, Sodium and Potassium.

The answer is (a) Be Mg Ca

• Metallic character increase as we move down the group. 
• In the elements that belong to same group Berrylium is at the top and Calcium is at the bottom.

(i) Increasing order of atomic mass and similarities in chemical properties of elements. 

(ii) The formula of oxides and hydrides formed by elements.

Down the group metallic character increases and across the period metallic character decreases. Only option (a) follows the right order.

Oxide formula → R₂O 

Hydride formula → RH. 

‘R’ represents element.

Scandium, gallium and germanium. 

Mendeleev left some gaps for undiscovered elements, because he predicted that there would be such elements which will fit in the gaps in future. He also predicted the properties of these elements.

It is because it resembles both with alkali metals as well as halogens.

(a) Salt is a compound formed by the partial or total replacement of the ionizable hydrogen atoms of an acid by a metallic ion or an ammonium ion.

(b) An insoluble salt can be prepared by precipitation.

(c) A salt prepared by direct combination is Iron (III) chloride.

Reaction:

2Fe +3Cl₂ 2FeCl₃

(d) The name of the procedure used to prepare a sodium salt such as sodium sulphate is Neutralization of acid with base.

Germanium was the element which found the place later in periodic table but Mendeleev predicted germanium to as eka-silicon.

Hydrogen had no fixed position in Mendeleev’s Periodic table because it resembles alkali metal by forming positive ions and resembles halogens by forming diatomic molecule.

Noble gases. Since they are chemically unreactive, so they got a place in the periodic table in the form of a separate group and hence did not disturb the original order of Mendeleev’s periodic table

Inert gases (Noble gases) could be placed in Mendeleev’s Periodic Table without disturbing the original order.

• Before Mendeleev Noble gases; like Helium. Neon and Argon had been mentioned by various scientists. 
• But these gases could be grouped together as noble gases much later than Mendeleev’s discovery.
• Mendeleev used 63 elements till his periodic table because these were the only known elements till his time. 
• However, he was bold enough to leave gaps in his periodic table. 
• He had predicted that that more elements would be discovered in times to come.
• Mendeleev’s Periodic Table was the first comprehensive attempt to classify elements on the basis of their chemical properties. 

This is the main reason that new elements could be easily placed in Mendeleev’s Periodic Table without disturbing the original order.

No. of electrons in one molecule of methane (CH₄)

= 6 + 4 = 10

No. of electrons in one mole of methane

= 10 x 6.023 x 10²³

= 6.023 x 10²⁴

Charge of one electron is 1.6 × 10⁻¹⁹ Coulomb.

The mass of one mole of electrons is :

6.023 × 10²³ × 9.1 × 10⁻³¹Kg = 5.48 × 10⁻⁷ Kg

The charge of one mole of electrons is:

6.023 × 10²³ × 1.6 × 10⁻¹⁹ Coulomb  

= 9.65 × 10⁴ Coulomb

1 mol = 6.023 x 10²³ units

Mass of 1 mol of electrons = Mass of an electron x 6.023 x 10²³

= 9.1 x 10^-31 kg x 6.023 x 10²³

= 5.48 x 10^-7 kg

Charge on 1 mol of electrons = charge on an electron x 6.023 x 10²³

= 1.602 x 10^-19 C x 6.023 x 10²³

= 9.65 x 10⁴ C.

The IUPAC name is CH₃ - CH₂ - CHO

Propanal.

3-Hydroxybutanoic acid/3-hydroxybutan-1-oic acid.

Mass of 1 mol of e- = 9.1 x 10^-31 x 6.022 x 10²³ kg = 54.8 x 10^-8 kg 

Charge of 1 mol e- = 1.6x10^-19 x6.022 x 10²³ = 96487 C

The animal bearing both male and female sex organs are called hermaphrodites. Example, earthworms, sponge and tapeworm.

(a) Pentane-2,4-dione

(b) 2-Ethylbutanal

(c) 3- Hydroxypentanal

Pent-3-yne-1-oic acid.

3- Aminobutanal.

In vegetative propagation, characters of parent plants are preserved

Pent -2-len-1-al.

The male gamete or male reproductive unit is called antherozoid or spermatozoa.

The unisexual male flower bearing stamens is called staminate.

Clone is not helping vegetative propagation. 

If a strip of silver metal is kept immersed in copper sulphate solution for some time, then no reaction occurs. This shows that silver is not able to displace copper from copper sulphate solution.

Heterothallic and dioecious.

Homothallic and monoecious.

(d) Pistillate

Blue color of copper sulphate is destroyed because iron displaces copper from copper sulphate solution as iron is more reactive than copper.

Bisexual animal — Earthworm 

Unisexual animal — Cockroach

Diamond. is very high melting point

Since graphite is a good conductor of electricity, it is used in making electrodes.

True

A solution of an ionic compound in water contains ions, which move to the opposite electrodes when electricity is passed through the solution.

False

Copper is below hydrogen in the reactivity series. Therefore copper cannot displace H from HCl.

i. In cyclohexanone, the carbonyl carbon is not hindered. Hence, the nucleophile CN^-ion can easily attack the carbonyl carbon. However in 2,2,6-trimethyl cyclohexanone, the carbonyl carbon is sterically hindered due to presence of methyl groups. Hence, the nucleophile CN^- ion cannot easily attack the carbonyl carbon.

ii. Out of two -NH₂ groups in semicarbazide, one is a part of amide functional group. In this, the lone pair on nitrogen atom is involved in the resonance with carbonyl group. Hence, this -NH₂ group cannot act as a nucleophile. Hence, it is not involved in the formation of semicarbazones.

iii. The formation of esters from a carboxylic acid and alcohol in the presence of an acid catalyst is a reversible reaction. If water or ester is not removed as soon as it is formed, the ester will hydrolyse to give starting materials carboxylic acid and alcohol.

False 

The hydrogen gas obtained from the reaction of metal and nitric acid is oxidized to water by nitric acid.

False 

Silver and gold do not react with oxygen at high temperatures.

True

Copper does not burn in air

True

Iron does not burn on heating but iron filings burn vigorously when sprinkled in the flame of the burner.

Vinegar IUPAC name is acetic acid CH₃COOH 

Functional group –COOH

X is ethanol (C₂H₅OH) and Y is ethanoic acid (C₂H₄O₂)

(C₂H₅OH) (X) \(\overset{Oxidation}\longrightarrow\) CH₃COOH (Y)

2CH₃COOH + Na₂CO₃ (Baking soda) → 2CH₃COOHNa + CO₂↑ + H₂O

RearIng: To take care and support up to maturity is called rearing.