Which of the following is a primary constituent of crude oil?
Pentane
Ethanol
Heptane
Methane
Correct answer is D
Crude oil is a mixture of hydrocarbons of various chain lengths. methane is one of the primary constituents of crude oil, and it belongs to the group of alkanes.
Which group does calcium belong to in the periodic table?
Alkaline earth metals
Halogens
Alkali metals
Noble gases
Correct answer is A
Calcium belongs to the alkaline earth metals group in the periodic table. It is located in Group 2 and has two valence electrons.
What is the principal ore of iron, from which iron is extracted?
Calcite
Bauxite
Magnetite
Hematite
Correct answer is D
Hematite (Fe\(_2\)O\(_3\)) is the principal ore of iron and is widely mined for the extraction of iron metal.
How many pi (\(\pi\)) bonds are there in an alkene with six carbon atoms?
4
6
5
3
Correct answer is A
In an alkene with six carbon atoms, there are 5 sigma (σ) bonds (single bonds) between the carbon atoms. Additionally, there are 4 pi (\(\pi\)) bonds associated with the double bonds between the carbon atoms.
Fe\(_3\)O\(_4\)
FeO
Fe(OH)3
Fe\(_2\)O\(_3\)
Correct answer is D
Rust is a reddish-brown compound that forms on the surface of iron in the presence of oxygen and moisture. Its chemical formula is Fe\(_2\)O\(_3\), indicating the presence of two iron atoms and three oxygen atoms in the compound.