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Correct choice is (b) 2 to 3%

To elaborate: Cement is an important building MATERIAL. The average composition of portland cement is calcium oxide of 50 to 60%, SILICON DIOXIDE of 20 to 25%, aluminium oxide of 5 to 10%, magnesium oxide of 2 to 3%, ferric oxide of 1 to 2% and sulphur trioxide of 1 to 2%.

The correct choice is (b) 49

The explanation: With an excess of dilute sulfuric acid and carbon dioxide, CALCIUM chloro hypochlorite FORMS chlorine, which is KNOWN as available chlorine. The average percentage of available chlorine is 35 to 40% but THEORETICALLY, it should be 49%, which DIMINISHES on keeping the Powder due to a chemical change.

The correct answer is (d) Painting

Easiest EXPLANATION: Calcium chloro hypochlorite or chloride of lime or BLEACHING powder which is chemically CaOCl2 is used for bleaching, as a DISINFECTANT and germicide in the sterilization of water, for making wool which is UNSHRINKABLE and in the manufacture of chloroform.

Correct choice is (b) Calcium chloro hypochlorite

To EXPLAIN I would say: CHLORIDE of lime is chemically KNOWN as calcium chloro hypochlorite and it is given by the chemical FORMULA CAOCL2, it is also known as bleaching powder. Bleaching powder is prepared by the fusion of calcium hydroxide and chlorine.

The correct choice is (a) Yes

To explain: When plaster of Paris or CALCIUM sulphate hemihydrate which is given by the chemical formula CaSO4.1/2H2O is mixed with water, it forms of plastic mass which sets into a solid mass with SLIGHT expansion due to dehydration and its REVERSE CONVERSION into GYPSUM.

Right CHOICE is (C) Anhydrous CALCIUM SULPHATE

Explanation: When plaster of Paris or calcium sulphate hemihydrate, which is given by the chemical formula CaSO4.1/2H2O is heated about 393 Kelvin, no water of crystallization is left and anhydrous calcium sulphate is formed, it is KNOWN as dead burnt plaster.

The correct answer is (b) False

Easiest explanation: Plaster of Paris is calcium sulphate hemihydrate and gypsum is calcium sulphate dihydrate. On HEATING gypsum at 390 Kelvin, it gives plaster of Paris. The CHEMICAL formula of gypsum and plaster of Paris is CaSO4.2H2O and CaSO4.1/2H2O RESPECTIVELY.

Right ANSWER is (a) CaSO4.2H2O

The best explanation: GYPSUM is a COMPOUND of calcium. It is chemically calcium sulphate DEHYDRATE and it is also known as alabaster. It is added to cement to SLOW down at speed of setting. It’s really very essential in our day to day life.

Correct answer is (a) Yes

The best EXPLANATION: Yes, limestone can be prepared through slaked lime. Limestone is calcium CARBONATE while slaked lime is calcium hydroxide. When limestone is PASSED through carbon dioxide, it RESULTS in the formation of calcium carbonate which is a precipitate and WATER.

Right option is (d) Calcium bicarbonate

To EXPLAIN I would say: When 1 mole of Calcium Hydroxide is treated with an EXCESS of CARBON dioxide in the presence of water, it results in the formation of calcium bicarbonate which is soluble. It is one of the most IMPORTANT properties of slaked lime.

Correct answer is (a) True

The explanation: Calcium carbonate is also known as limestone or marble are chalk, its chemical FORMULA is given by CaCO3. It is INSOLUBLE in WATER but dissolves in the presence of CARBON DIOXIDE due to the formation of calcium bicarbonate.

Right choice is (a) True

The EXPLANATION: Yes, CALCIUM oxide chemical formula is CaO and it is also called as quicklime or simply lime. It is prepared by the thermal DECOMPOSITION of calcium carbonate at 1072-1270 Kelvin, carbon dioxide comes as a BYPRODUCT and it is a BASIC oxide.

Right answer is (a) Phenol

To explain I would say: QUICKLIME or CALCIUM oxide (CaO) is used as a basic flux, for removing the hardness of WATER, also used in mortar. A mixture of quick lime and sand in the ratio 1:3 with enough water to make a thick place is called MOTOR.

Right choice is (b) 63 kJ/mol

Best explanation: Calcium hydroxide is prepared by dissolving quicklime and water and the enthalpy change for this reaction is 63 kJ/mole (the sign is NEGATIVE). Here the chemical formulae for quicklime and Calcium hydroxide are CAO and CA(OH)2 has twice respectively.

Correct choice is (B) beryllium and aluminium share a DIAGONAL relationship

For explanation: The correct statement is a beryllium and aluminium share a diagonal relationship, as aluminium and beryllium are STABLE in air, the ionization potential of beryllium has HIGHER comparatively with its group and it has a LOWER oxidation potential.

Right CHOICE is (C) Calcium hydroxide

For EXPLANATION: When 1 mole of burnt lime, that is calcium oxide is combined with 1 mole of the hydrogen molecule, a HISSING sound appears and SLAKED lime is produced along with the heat. The chemical formula for slaked lime Ca(OH)2.

Right answer is (a) Yes

Explanation: Beryllium and ALUMINIUM FORM a number of COMPLEXES both form FLUORO complex and IONS, this is one of the similar chemical properties between beryllium and aluminium as they share a diagonal relationship.

Right choice is (b) ELECTRONEGATIVE

Explanation: Beryllium’s and aluminium action with water is the same, they do not DECOMPOSE with water or in the presence of water even at hundred degrees centigrade. This is probably due to their less ELECTROPOSITIVE CHARACTER that is they are electronegative in nature.

Right answer is (c) Na2Al2O4

To elaborate: When aluminium reacts with alkali, that is when ONE MOLE of aluminium reacts with two moles of sodium HYDROXIDE in presence of two moles of water two moles of sodium meta aluminate is formed ALONG with THREE moles of hydrogen. The chemical formula for sodium meta aluminate is Na2Al2O4.

Right answer is (c) passive

Easy explanation: Aluminium and BERYLLIUM are RENDERED passive on reaction with concentrated nitric acid, due to the FORMATION of the oxide layer on their SURFACES, this is one of the similarities between aluminium and beryllium.

Right ANSWER is (a) true

To ELABORATE: BERYLLIUM when heated with CARBON forms beryllium carbide which on reaction with water gives methane, while the other MEMBERS of the group form ionic carbide which is acetylide which on reaction with water evolves acetylene.

The CORRECT choice is (c) amphoteric

For explanation I would say: Beryllium oxide (BEO) and beryllium HYDROXIDE [Be(OH)2] are amphoteric in character they ALSO dissolve in ACID to form a salt and beryllate in alkali. Beryllate is any salt containing an anion BeO2^2-.

Right choice is (B) No

The best explanation: Beryllium does not react with WATER even at a higher temperature while the other members of the FAMILY liberate hydrogen by reacting with water at ROOM temperature, this is also one of the reasons of the ANOMALOUS behaviour of beryllium.

Correct OPTION is (c) higher, HARDER

Easy explanation: The points of difference are that the beryllium is denser and harder than other MEMBERS of its FAMILY and it has a higher MELTING point that is 1551 Kelvin while that of magnesium is just 924 Kelvin. So we can say that beryllium has a higher melting point and is harder than other members of its family.

Correct choice is (B) beryllium

To explain I would say: Beryllium, DIFFERS from the rest of the members of its GROUP due to the following REASONS: beryllium has a small atomic and ionic size, it has no vacant d-orbitals and it has a HIGHER charge density comparatively.

Right option is (d) barium

The explanation: Magnesium COMBINES with few elements like ALUMINIUM, manganese, ZINC and TIN in ORDER to form a lot of magnesium aluminium alloys which are very light in mass and are used in the construction of aircraft. There are also many other uses of magnesium.

Right OPTION is (b) No

The best explanation: All the alkaline earth metals (except BERYLLIUM) their hydrides can be PREPARED by combining with HYDROGEN. We can prepare beryllium hydride, through HEATING beryllium chloride with lithium aluminium hydride.

Right choice is (c) less than

Easiest explanation: ALTHOUGH the alkaline earth METALS are reductants in nature, their reducing POTENTIAL is not as greater as alkali metals. Beryllium has a negative value when compared to the other elements in its group, this is due to the LARGE hydration energy associated with the small size of beryllium.

The correct choice is (c) thermal decomposition of (NH4)2BeF4

The BEST I can explain: All the alkali Earth metals combine with halogen at elevated TEMPERATURES forming their halides, the thermal decomposition of (NH4)2BeF4, is best road and to prepare BEF2 and BeCl2 is conveniently MADE from the oxide.

Right answer is (c) beryllium nitride

Easiest explanation: We KNOW that beryllium is KINETICALLY inert to Oxygen and water as it FORMS oxide FILM on the surface. But WHEREAS powdered beryllium burns brightly on ignition in the air in order to give the oxides and nitrides of beryllium.

The correct answer is (b) Be^+2 > Mg^+2 > Ca^+2 > Sr^+2 > Ba^+2

The best explanation: The hydration enthalpy decreases with the INCREASE in ionic size along with the group TOWARDS down, the correct ORDER of hydration enthalpy is GIVEN as Be^+2 > Mg^+2 > Ca^+2 > Sr^+2 > Ba^+2 and the hydration enthalpies of alkaline earth metal IONS are greater than the size of alkali metal ions. We can say that these are extensively hydrated than them.

The CORRECT option is (C) apple green

Explanation: The COLOURS of Barium, Strontium and Calcium are Apple Green, Crimson and brick red. These are the colours of their FLAMES, the colours occur when an electron is excited and jumps into a higher energy level and then drop BACK. They emit the radiation in the form of visible light.

The correct CHOICE is (b) 2

For explanation: The alkaline earth METALS have two electrons in the s-orbital of their valence shell and their GENERAL electronic configuration as represented as ns^2. Similar to the alkali metals these elements compounds are PREDOMINANTLY IONIC.

Correct choice is (a) beryllium

Explanation: Beryllium, BELONGS to the 2^nd GROUP. It is not called as an alkaline EARTH metal because the first element of this group that is beryllium is different from the rest of the members and it ALSO shows a diagonal relationship with ALUMINIUM.

Right option is (a) Yes

The best I can explain: Potassium carbonate can be used instead of sodium carbonate as an antacid, in case if the PERSON who has to CONSUME antacid is restricted to consume sodium. This is because Sodium and potassium belong to the same group and have SIMILAR properties.

The correct choice is (b) rubidium

Explanation: Rubidium accumulates in muscle ahead of potassium and it can stimulate metabolism. It ALSO READILY reacts with SKIN moisture in order to form rubidium hydroxide. This is the biological IMPORTANCE of the element rubidium.

Right OPTION is (c) no

The best EXPLANATION: No, cesium cannot be INGESTED, it should be AVOIDED this is because the similarity of the ISOTOPES of cesium present in the biosphere is very toxic and there ingestion can be dangerous and hazardous.

Correct answer is (B) no

Best explanation: There is no biological importance of the alkali metal francium. Francium is a highly radioactive element and its CHEMICAL hazards are similar to those of cesium. Francium is not AVAILABLE to a significant extent in the BIOSPHERE.

Right option is (a) cold

For EXPLANATION: Muscle weakness, paralytic ileus, acidosis, ECG ABNORMAL 38, inflammatory bowel diseases, RESPIRATORY paralysis, alkalosis, cardiac AHEAD, RENAL damage, muscle contraction, and hypokalemia are treated using higher levels of potassium.

Correct option is (b) lithium

Easiest explanation: Lithium carbonate is a drug which is used to treat depressive disorders for Hypertension, lithium chloride is also used as a TREATMENT. Lithium cannot be CONSUMED DIRECTLY because it has an effect on the BODY.

The correct option is (c) ONE third

Explanation: The Sodium-Potassium pump OPERATES across CELL membranes and consumes around one-third of the ATP used by a resting person. Sodium ion and potassium ions levels change within red blood cells because of the DISCRIMINATORY mechanism CALLED is the Sodium-Potassium pump.

Right answer is (b) false

Explanation: Though potassium and sodium are similar chemically, they differ in their ability to penetrate the cell MEMBRANE and ALSO in the mechanism of their TRANSPORT. Potassium is more efficient in case of ACTIVATING enzymes.

Correct answer is (c) sodium

Best EXPLANATION: Sodium, being an alkali metal has many BIOLOGICAL USES like NERVE signal transmission, also in WATER flow regulation across cell membranes along with the Sugars and amino acids’ transportation into cells.

The correct choice is (c) 5 gram

For explanation: An ideal person, who is of 70 kg contains about 90 GRAMS of sodium, 5 grams of iron, 170 grams of potassium and 0.06 grams of COPPER. We can say that there is a great biological importance of ALKALI metals.

Correct choice is (b) causticizing process

To explain: A 10 percent solution of sodium carbonate is treated with milk of LIME, this is KNOWN as causticizing process and is one of the methods of preparation of sodium hydroxide, sodium carbonate reacts with CALCIUM hydroxide to FORM calcium carbonate as precipitate and sodium hydroxide.

Correct option is (b) false

The explanation: The physical properties of sodium hydroxide are that it is white translucent SOLID, readily soluble and water as the CRYSTALS of sodium hydroxide a DELIQUESCENT in nature. It is also KNOWN as caustic soda.

Correct ANSWER is (c) Sodium HYDROXIDE is formed

Explanation: In the electrolytic process, which involves Nelson CELL and castner kellner cell, the sodium amalgam is TREATED with water to give sodium hydroxide, hydrogen gas, and mercury. Sodium amalgam is formed when sodium metal discharges at the mercury cathode COMBINING with mercury.

The CORRECT choice is (b) common Ion effect

Best explanation: The sodium chloride that’s OBTAINED by seawater evaporation, is purified by passing through HCl gas through the impure saturated solution of NaCl and due to common Ion effect, pure NaCl gets precipitated 28% of NaCl solution is CALLED Brine.

Correct option is (B) deliquescent

The EXPLANATION: DELINQUENCY is a tendency to dissolve. Sodium chloride is obtained by evaporation of SEAWATER but due to the presence of impurities like calcium chloride and magnesium chloride, it has deliquescent NATURE.