2) Expansion of substances when heated is an example of a chemical change.
3) Mercury and water form a homogeneous mixture.
4) Methyl alcohol can be separated from methyl alcohol -- water mixture using a separating funnel.
5) The formula of sodium chlorate is NaClO.
6) The valency of sodium in sodium sulphite - Na₂SO₃ is 2+
7) Reaction of silver nitrate with sodium chloride is an example of a displacement reaction.
8) 0°C is equivalent to -273K on the Kelvin scale.
9) As per Charles Law equation P₁V₁ = P₂V₂= K (constant)
10) The component of air which is an essential constitution of plant proteins is oxygen.
11) Oxygen and nitrogen are non supporters of combustion.
12) Percentage of nitrogen in inspired air is more than in respect air.
13) Separation of components of air is possible by preferential liquefaction.
14) Water at 4°C has minimum density and minimum volume.
15) Dissolved air in water contains a lower percentage of O₂ than ordinary air.
16) Sulphide dioxide dissolves in water to give sulphuric acid.
17) A saturated solution cannot dissolve more of the solvent at a given temperature.
18) Solubility of CaSO₄ increases KNO₃ decreases with rise in temperature.
19) A decrease in pressure and temperature causes decrease in solubility of gas in water.
20) Fused calcium chloride is efflorescent and hence used as a desiccating agent.
21) A proton has a positive charge and negligible mass.
22) Mass number of an element is the sum number of electrons and protons in the atom.
23) An element X having electronic configuration 2,8,2, has a valency of -2.
24) Isotopes have the same number of protons and electrons but in electronic configuration.
25) A covalent bond is formed by electron sharing between a metallic and a non metallic element.
26) The first element of the periodic table doesn't contain any protons.
27) In a compound having the formula H₂Z, the valency of Z is+1.
28) Li(at. no. 7), Na(at. no. 23), and K(at. no.39) represented Dobereiner Law of Octaves.
29) Mendeleef arranged elements in seven horizontal rows and eighteen vertical columns.
30) Isotopes having different atomic weights had the same position in Mandeleef's table.
31) The number of valence electrons represent the period number of the periodic table.
32) Elements of group IA, VIIA and zero are highly reactive.
33) All alkali metal are electronegative and lose electrons forming anions.
34) Hydrogen is a non and forms electrovalent compound only with metals.
35) Zinc, iron and lead react with dilute sulphuric acid liberating hydrogen.
36) Hydrogen is lighter than air, fairly soluble in water and easy to liquefy.
37) Hydrogen removes oxygen from heated metallic oxides and is itself reduced to water.
38) Carbon atomic no.6 has six valence electrons and placed in group VIA of the periodic table.
39) Carbon is the only element of its group exhibiting allotropy.
40) Graphite and lampblack are micro- crystalline allotropes of carbon.
41) Destructive distillation of wood gives wood tar as the only liquid product.
42) Passage of steam over heated coke results in formation of producer gas.
43) Nitrogen, phosphorus and sulphur are group VA elements.
44) Ammonium nitrate decomposed to give water and nitrogen.
45) Nitrogen is highly reactive due to presence of a strong triple covalent bond.
46) Nitrosifying bacteria convert nitrates to free nitrogen in the atmosphere.
47) Oxygen (at no 8) and sulphur (at no 16) are elements of the same group and period.
48) Lower oxides of lead decompose to give a higher oxide and oxygen.
49) Rusting is slow reduction of iron its oxide -- hydrated iron (III) oxide.
50) Extraction of sulphur of higher purity is obtained by the Sicilian Process.
51) Metals react with sulphur only in the heated state.
52) Elements of group VIIA and VIA are all nonmetals.
53) Chlorine oxidised hydrogen Sulphide to hydrogen chloride.
54) Chlorine and iodine displaces bromine from potassium bromide.
55) Chlorine bleaces both coarse and delicate fabrics by reduction.
56) CO₂ can be converted to CO by passage over heated copper (II) oxide.
57) Liquid carbon dioxide is called dry ice.
58) Thermal decomposition of limestone is called slaking of lime.
59) Heat on lead(IV) oxide leaves a black residue which fuses with the glass.
60) Temporary and permanent hard water can be softened by boiling.
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