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The children were delighted that the exams had been canceled.

This is the place where the dog was rescued from its cruel owner.

When she finished the cooking she lied on the table.

Despite of being old, he still works hard.

I asked the delivery boy, ―Could you bring the parcel tomorrow / the next day?

Sheila's grandmother found it difficult to climb up the steep staircase

The most ill-fitted suit that I have ever worn.

Anil is so fast runner that he could not come first in the race.

There is no family without a black sheep.

The poet' s mother was stung by a scorpion.

Mild mental retardation :

IQ range: 55-69 (constitutes 85% of the total population with mental retardation). 

Moderate mental retardation : 

IQ range : 40-54 (constitutes 10% of the total population with mental retardation) 

Description: 

Mild mental retardation: 

Academics : Slow learners in school, repeats early grades but are educable. They are able to grasp concrete concepts much better than abstract concepts. They are able to read and write and solve simple mathematical problems. Comprehension comes from experience. Since their experience is limited, comprehension is limited. Sustaining attention for a long time becomes difficult for these children. 

Social skills : Social adjustment is comparable to an adolescent ; they have friends and adjust fast.

Moderate mental retardation: 

Academics : Inadequate academic skill, not educable but trainable. With early diagnosis , parental help and. adequate training most of them can achieve considerable independence in all spheres of life. 

Social skills : Might have friends but face difficulty in social situations.

Ionic compounds have alternatively arranged cations and anions to give closely packed structure and balanced forces. A lot of energy is needed to break strong ionic bonds therefore ionic compounds have high melting point.

Acetic acid is weak electrolyte which dissociated partially whereas HCl is strong electrolyte which dissociate completely therefore HCl is better conductor compared to CH₃COOH.

Alkali metals have large size and single electron in valence shell. This e– can be easily lost therefore alkali metals are good reducing agents (e– donors)

Ionic or electrovalent compounds do not conduct electricity in their Solid  state. 

On a account of highly stable configuration in the valency shell, these elements have no tendency either to lose, gain or share electrons with the atoms of other elements.

(i) SO₂

(ii) H₂S

(iii) NO₂

(iv) O₂

(v) H₂

From left to right in periodic table, atomic size decreases smaller the size more the effective nuclear charge.Therefore more energy is required to remove an electron from atom therefore ionization potential increases.

Br₂ gas is released with brown fumer.

Inert gases have stable completely filled orbitals hence they do not loose or gain electron to form ions.

Inert gases do not form ions because their outermost orbital is complete and they have a stable electronic configuration.

1. Conc. Sulphuric acid 

2. Conc. Sulphuric acid 

3. Nitric acid 

4. Sulphuric acid 

5. Hydrochloric acid

Ionic compounds have high melting points because the ionic bonds that hold the compounds together are very strong and require a great deal of energy to break the bond.

(i) Copper 

(ii) Sodium argento cyanide 

(iii) molecules 

(iv) Carboxylic acid 

(v) Ammonium chloride

23 g of sodium → 1 gram atom

1 g of sodium → \(\frac{1}{23}\) gram atom

4.6 g of sodium → = \(\frac{1}{23}\times\frac{4.6}{10}\,=\frac{2}{100}\) = 0.02gatoms

Brown fumes of bromine gas are observed at anode

When barium chloride is added to sodium sulphate, the products are sodium chloride (which remains in the solution) and barium sulphate precipitate (which settles down as a white precipitate). 

BaCl₂ + Na₂SO₄ ------> BaSO₄ + 2NaCl

(i) On dropwise addition of sodium hydroxide solution to lead nitrate solution it first gives a white precipitate and then on adding excess of sodium hydroxide solution, a clear solution is obtained due to formation of sodium plumbate (Na₂PbO₂) which is colourless and soluble.

Pb(NO₃)₂ + 2NaOH ---> Pb(OH)₂ (↓) + 2NaNO₃ 

Pb(OH)₂ + 2NaOH (Excess) ---> Na₂PbO₂ 

(ii) At the anode, when lead bromide is electrolyzed using graphite electrodes following reaction occurs at the anode during electrolysis :

2Br^- + 2e^- ---> Br₂(↑) 

(iii) Lead nitrate solution is mixed with dilute hydrochloric acid and heated to give lead chloride and nitric acid : 

Pb(NO₃)₂ + 2HCl --> PbCl₂ + 2HNO₃ 

(iv) Anhydrous calcium chloride is exposed to air for some time and it absorbs moisture from air as it has a strong affinity for water : 

CaCI₂ + 2H₂O ---> Ca(OH)₂ +2HCl

(v) Barium chloride solution is slowly added to sodium sulphate solution to obtain barium sulphate : 

BaCl₂(aq) + Na₂SO₄(aq) ---> BaSO₄(s) + 2NaCl(aq)

MgSO₃ + 2HCl → MgCl₂ + H₂O + SO₂

1. Insoluble chalky white ppt of lead hydroxide is obtained. 

2. Reddish brown colour of bromine water disappears.

3. The blue colour of copper sulphate solution disappears. 

4. Reddish brown fumes of nitrogen dioxide a colourless gas that rekindles a glowing splint are released. In the test tube, a ppt is left which is yellow when hot and white when cold. 

5. Insoluble reddish brown ppt obtained

(i)  A white ppt. of lead hydroxide

(ii)  A colorless solution is obtained and brown color of bromine vapors disappear.

(iii)  A red shiny metal starts precipitating

(iv)  A reddish brown gas is liberated.

(v)  A reddish brown ppt. of ferric hydroxide is formed which remains insoluble in excess of sodium hydroxide.

The ratio between the number of molecules in 2 g of hydrogen and 32 g of oxygen is 1 : 1.

The ratio between the number of molecules in 2 g of hydrogen and 32 g of oxygen is 1 : 1.

(D) Copper and tin

(i) Hydrogen chloride 

(ii) Nitric oxide 

(iii) Ammonia 

(iv) Hydrogen sulphide

(B) Mainly ions

The two main metals in bronze are Copper and tin.

The particles present in strong electrolytes are mainly ions.

(i) (E), 

(ii) (C), 

(iii) (B), 

(iv) (D), 

(v) (A)

1. (E) 

2. (C) 

3. (B) 

4. (D) 

5. (A)

1. Hydrogen chloride gas 

2. Nitric oxide 

3. Oxygen 

4. Ammonia 

5. Hydrogen sulphide

1. Ionization potential is defined as the energy required to remove an electron from a neutral isolated gaseous atom to convert it into a positively charged gaseous ion.

2. Electron affinity is the amount of energy released. While converting a neutral gaseous isolated atom into a negatively charged gaseous ion when an extra gaseous electron is added to the atom.

1. Bluish white precipitate appears which dissolves in excess of NH4OH and give an inky blue solution of tetra amino copper sulphate. 

2. A gelatinous white precipitate appears which dissolves in excess of NH₄OH and give a clear transparent colourless solution of tetra amine zinc sulphate.

1. Period = 3 

2. No. of valence electrons = 6 

3. It is a non metal.

(i) 1. Ionic bond

2. Covalent Bond

(ii) 1. ZX

2. WX

1. No. of Valence electrons in atom J = 5

2. Element M

3. Element T is more reactive than R. 

4. Element T has its electrons arranged in four shells

(i) Metallic

(ii) Smallest

I don' t know what they were arguing about but I could hear angry voices.

There is no use crying for spilled milk.

The term ‘racism’ is an ideology that promotes discriminative practices towards people based on their race or ethnicity. Racism is the belief in the superiority of one race over another, which often results in discrimination and prejudice towards people based on their race or ethnicity. Racism can be present in social actions, practices, or political systems.