Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
In a flame test for calcium, the flame appears
green when viewed through a blue glass
blue when viewed through a blue glass
orange -red when viewed through a blue glass
brick-red when viewed through a blue-glass
Correct answer is A
When a Calcium compound is held in a non-luminous Bunsen flame and viewed directly with the naked eye, it is seen as brick red,then as light green as seen through blue glass.
The property used in the industrial preparation of nitrogen and oxygen from air is?
rate of diffusion
density
boiling point
solubility
Correct answer is C
Fractional distillation of liquefied air, with Nitrogen distilling as a vapor at a lower boiling point of -196°C while O2 is left as a liquid.
The ores that can be concentrated by flotation are
nitride ores
sulphide ores
oxide ores
non-metals
Correct answer is B
No explanation has been provided for this answer.
Metalliods are also referred to as
semi-metals
metals
colliods
non-metals
Correct answer is A
No explanation has been provided for this answer.
The most abundant element on the earth's crust is
nitrogen
hydrogen
oxygen
flourine
Correct answer is C
- The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen.
HOWEVER;
- Earth's crust is made up of several elements: oxygen, 46.6 percent by weight; silicon, 27.7 percent; aluminum, 8.1 percent; iron, 5 percent; calcium, 3.6 percent; sodium, 2.8 percent, potassium, 2.6 percent, and magnesium, 2.1 percent.
- This implies that Oxygen is the most abundant element (by mass) in the Earth's crust, making up almost half of the crust's mass