A student subtracted 0.00055 from 10.2345678 and reported the result as 10.23401. But his friend told him that the result was wrong. What is the correct result?
A. 10.234017
B. 10.2340178
C. 10.234
D. 10.23
The following statement contained in a student’s laboratory report is a conclusion.
A. a gas is liberated
B. colour of the gas is greenish yellow
C. oxide of the gas is strongly acidic
D. the gas is chlorine
A 50.00 mL sample of a cough mixture prepared by a pharmacist was found to have a mass of 46.0g. what is the density (in g/mL) of this mixture. Stated to the correct number of significant figures?
A. 0.92
B. 0.920
C. 0.9200
D. 1.087
Tobacco contains a poisonous alkaloid called Nicotine. The molecular formula of nicotine is C10H14N2 (molar mass = 162.23g). The mass percentage of nitrogen in nicotine, is?
A. 4.32%
B. 8.23%
C. 12.4%
D. 17.3%
A sample of an ionic compound contains 2.82 g Na, 4.35 g CI, and 7.83 g O. The empirical formula of this compound is:
A. NaClO2
B. NaCIO3
C. NaCIO
D. NaCIO4
Professor Anwar told his students that air is a mixture because: suddenly a student raised his hand and said
A. it is colourless
B. oxygen can be removed from it
C. its composition is different at different altitudes
D. it has different properties from its constituents
Imagine Dr. Khan is sitting in a room. The room is closed from all sides, no entry, no exit of any gas. If the room expands suddenly then
A. he will be frightened
B. his blood pressure will decrease
C. he will feel cool
D. he will feel warmth
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