To find the number of neutrons in sodium (Na) and magnesium (Mg), we subtract the atomic number from the atomic mass: Sodium (Na) has an atomic number of 11 and an atomic mass of 23. Neutrons = 23 – 11 ...
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The molecular mass of glucose (C6H12O6) is calculated by adding the atomic masses of its constituent atoms: 6 carbon (12 u), 12 hydrogen (1 u), and 6 oxygen (16 u). This gives a total of 180 u. So, the correct ...
The correct answer is: (c) Atoms of same or different elements can join together to form molecules. Molecules are formed when atoms of either the same element (e.g., O₂) or different elements (e.g., H₂O) bond together. The combination of atoms ...
Magnesium (Mg) and sulfur (S) combine to form magnesium sulfide (MgS) according to the reaction: Mg + s → From atomic masses: Magnesium (Mg) = 24 g/mol Sulfur (S) = 32 g/mol The ratio of magnesium to sulfur in MgS is:
(a) +3 and -3 respectively. Aluminium (Al) has a valency of +3 because it loses three electrons to achieve stability. Phosphate (PO₄³⁻) has a valency of -3 as it gains three electrons. They combine to form AlPO₄ in a neutral ...
The correct answer is (b) John Dalton. John Dalton proposed the first atomic theory in the early 19th century, which stated that matter is made up of indivisible particles called atoms, and that atoms of the same element are identical ...
The correct answer is (c) atomic mass units. The relative mass of a molecule is expressed in atomic mass units (amu) or daltons (Da). This unit compares the mass of a molecule to the mass of an atom of carbon-12, ...
The correct answer is (c) law of conservation of mass. This law, proposed by Antoine Lavoisier, states that mass cannot be created or destroyed in a chemical reaction. The total mass of reactants before a reaction is equal to the ...
The correct answer is (d) Al. The chemical symbol of aluminium consists of a capital letter ‘A’ followed by a lowercase ‘l’. Chemical symbols always start with an uppercase letter, and if there is a second letter, it is lowercase.
The correct answer is (b) atom. According to Greek philosophers, especially Democritus, the smallest particle of matter that could not be further divided was called the “atom” (from the Greek word “atomos,” meaning indivisible). Modern science later refined this concept.