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| | 1) Sodium: | |
| | a: is an alkaline metal |
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| | b: is a mamber of the alogens |
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| | c: has no unpaired electrons |
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| | d: has one unpaired electron that shares in covalent bonds |
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| | 2) Nitrogen in many compounds forms three chemical bonds because: | |
| | a: it is a member of the third group |
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| | b: it has a high electronegativity |
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| | c: it has three unpaired electrons |
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| | d: it can form three coordination bonds |
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| | 3) The ionic properties of the bond of an atom A with an atom of chlorine: | |
| | a:are always negligible |
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| | b: increase as the electronegativity of A increases |
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| | c: increase as the electronegativity of A decreases |
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| | d: do not depend on the electronegativity of A |
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| | 4) Two containers of identical volume contain equal masses of two different gases, both ideal, at the same temperature. | |
| | a: the gas with higher molecular weight exerts higher pressure |
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| | b: the pressures of the two gases bear no relationship with their respective molecular weight |
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| | c: the two gases exert the same pressure |
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| | d: the gas with lower molecular weight exerts higher pressure |
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| | 5) The molar fraction of a gas in a mixture: | |
| | a: is identical, except for the factor of 100, to the volume percentage |
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| | b: is identical, except for the factor of 100, to the weight percentage |
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| | c: is the ratio between the mass of the gas and the mass of themixture |
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| | d: is independent on the partial pressure of the gas |
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| | 6) 0,93 g of a gaseous substance that does not dissociate at P=700 mmHg and T=27oC occupy a volume of 250 mL. Which is the molecular weight of this compound? | |
| | a: 49 |
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| | b: 99 |
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| | c: 119 |
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| | d: 199 |
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| | 7) A mixture containing 50 g O2 and 50 g CO exerts the total pressure of 600 mmHg. DEtermine the partial pressures of the two gases (in atm)? (P.A. O = 16, C = 12) | |
| | a: 0.789 atm and 0.789 atm |
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| | b: 0.394 atm and 0.394 atm |
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| | c: 0.320 atm and 0.469 atm |
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| | d: 0.368 atm and 0.421 atm |
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| | 8) Determine the molarity of a solution prepared by diluting 100 mL of nitric acid 0.2 M with water, to the final volume of 500 mL. | |
| | a: 0.1 M |
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| | b: 0.05 M |
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| | c: 0.04 M |
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| | d: 0.02 M |
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| | 9) 100 mL of 0.5 N HClare mixed with 150 mL of 0.1 N HCl. Determine the normality of the solution thus obtained. | |
| | a: 0.10 N |
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| | b: 0.26 N |
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| | c: 0.40 N |
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| | d: 0.50 N |
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| | 10) Determin the molarity of a 3 m solution of ammonia (MW=17), with density 0.98 g/mL. | |
| | a: 3.1 M |
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| | b: 3.0 M |
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| | c: 2.9 M |
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| | d: 2.8 M |
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