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.
What is the molar mass of water (H2O)?
18 g/mol
22 g/mol
16 g/mol
12 g/mol
Correct answer is A
The molar mass of water (H2O) is calculated by adding the atomic masses of its constituent elements: 2 hydrogen atoms (each with a molar mass of approximately 1 g/mol) and 1 oxygen atom (with a molar mass of approximately 16 g/mol). Therefore, the molar mass of water is 2 x 1 g/mol + 1 x 16 g/mol = 18 g/mol.