Answer: option (3) SrO, with 84.56%
Explanation:
You have to calculate the mass of strontium and the mass of the compound, for each of the four compounds, and compute the percent:
percent of strontium = (mass of strontium / mass of the chemical formula) × 100 %.
These are the atomic masses of the elements that you have to use:
Atomic mass of Sr: 87.62 g/mol
Atomic mass of Cl: 35.453 g/mol
Atomic mass of I: 126.904 g/mol
Atomic mass of O: 15.999 g/mol
Atomic mass of S: 32.065 g/mol
(1) SrCl₂:
i) mass of Sr: 87.62 g/mol
ii) mass of Cl₂: 2×35.453 g/mol = 70.906 g/mol
iii) mass of SrCl₂: 87.62 g/mol + 70.906 g/mol = 158.526 g/mol
iv) Sr % = [87.62 / 158.526 ] × 100 = 55.27%
(2) SrI₂
Following the same procedure:
i) Sr % = [87.62 / (87.62 + 2× 126.904) ] × 100 = 25.66%
(3) SrO
i) Sr % = [87.62 / (87.62 + 15.999) ] × 100 = 84.56%
(4) SrS
i) Sr % = [87.62 / (87.62 + 32.065) ] × 100 = 73.21%
(1) Ag (3) Cu
(2) Au (4) Pb
Answer is (4) - Pb.
According to the reactivity series of elements
- the elements which are above the hydrogen are more reactive than hydrogen.
- the elements which are below the hydrogen are less reactive than hydrogen.
Among the given choices, only Pb is placed above the hydrogen in the reactivity series and rest are below the hydrogen.
Hence, Pb is more active than hydrogen.
3
4
8
16
Answer:
3
Explanation:
Answer:
Explanation:
A pure substance is a substance that consists of only one type of particle, either atoms, molecules, or ions, and has a consistent and uniform composition throughout. Pure substances cannot be separated into other substances by physical means. They have well-defined chemical properties and distinct physical properties, such as melting point and boiling point.
Two examples of pure substances are:
Elemental Hydrogen (H2): Elemental hydrogen consists of diatomic molecules, each containing two hydrogen atoms bonded together. It is a pure substance because it consists only of hydrogen molecules and cannot be separated into other substances without chemical reactions.
Water (H2O): Water is a pure substance composed of water molecules, each consisting of two hydrogen atoms and one oxygen atom bonded together. It is also a pure substance because it has a consistent and uniform composition throughout and cannot be separated into other substances without breaking its molecular bonds.
These examples illustrate the concept of pure substances, where the composition is homogeneous and consistent throughout the entire sample.