Practice Pakistan questions with answers and explanations.
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A physical change alters form or state without changing chemical identity.
Ice and liquid water are both H2O.
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Rusting forms new iron oxide substances.
Chemical changes involve rearrangement of atoms and new products.
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Density describes how much mass is packed into a volume.
It is commonly expressed in g/cm³ or kg/m³.
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The mole is the SI base unit for amount of substance.
One mole contains Avogadro's number of specified entities.
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Avogadro's constant gives the number of entities in one mole.
The entities may be atoms, molecules, ions, or formula units.
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Molar mass is numerically related to relative atomic or molecular mass.
Its common unit is g/mol.
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The metre is the SI base unit of length.
Other metric length units are derived from it using prefixes.
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The kilogram is the SI base unit of mass.
The gram is one-thousandth of a kilogram.
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The second is the SI base unit of time.
Minutes and hours are accepted non-SI units derived from it.
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A scalar has magnitude only.
Speed has no associated direction.
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All organisms are made of one or more cells.
Cells perform the fundamental processes required for life.
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Modern cell theory states that cells come from existing cells.
Cell division provides continuity of life.
