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 (Fe2O3) is the principal ore of iron and is widely mined for the extraction of iron metal.
How many pi (π) 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 (π) bonds associated with the double bonds between the carbon atoms.
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.