chemistry for grade 7

1. First period The first period has two elements - hydrogen and helium. 2. Second and third period The second and third periods are known as short periods. Each consists of eight elements. The second period starts with lithium (Z = 3) and ends with inert gas neon (Z = 10)...

1. First period - The first period has two elements - hydrogen and heliu..

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The Seven Crystal System - Crystals along with suitable examples are listed in the table. System Axial distances Axial angles Examples Cubic a = b = c α = β = γ = 90° NaCl,KCl, Diamond, Cu, Ag Tetragonal a = b ≠ c α = β = γ = 90° White tin,SnO ..

2 SO 4 .10H 2 O Hexagonal a = b ≠ c α = β = 90°, γ = 120° Graphite, ZnO, CdS Rhombohedral a = b = c α = β = γ ≠ 90° Calcite, quartz, NaNO 3 Triclinic a ≠ b ≠ c α ≠ β ≠ γ ≠ 90° ..

Quantity Unit Symbol Length metre m mass kilogram kg Time second S Temperature kelvin K Amount of Substance mole mol Electric current ampere A Luminous intensity candela Cd ..

Reaction takes place in acidic medium, so add H+ ions to the side deficient in H+ and balance H and O atoms..

Calculate the vapor density and molecular weight of CO 2 gas occupying 200 mL and weighing 0.40 g at ST..

How many grams of pure sulphuric acid is present in 0.05 mole of it? (H=1, S=32, O=1..

The molecular mass (or molar mass) is obtained either from the experimental data or from the vapor density of the compound by using the relationship, Molecular mass = 2 x Vapor dens..