Agas diffuses 1/8 times faster than hydrogen gas. what is the molar mass of the gas?
129.02 g/mol
136.44 g/mol
140.81 g/mol
145.45 g/mol

129.02 g/mol.

Explanation:

∨ ∝ 1/√M.

where, ∨ is the rate of diffusion of the gas.

M is the molar mass of the gas.

∵ ∨₁/∨₂ = √(M₂/M₁).

∨₁ is the rate of effusion of H₂ gas.

∨₂ is the rate of effusion of the unknown gas.

M₁ is the molar mass of H₂ gas (M₁ = 2.016 g/mol).

M₂ is the molar mass of the unknown gas (M₂ = ??? g/mol).

∨₂ = 1/8∨₁

∨₁/∨₂ = 8.0.

∵ ∨₁/∨₂ = √(M₂/M₁)

∴ (8.0) =√(M₂)/(2.016 g/mol)

∴ (8.0)² = (M₂)/(2.016 g/mol)

∴ M₂ = (8.0)²(2.016 g/mol) = 129.024 g/mol ≅ 129.02 g/mol.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.