Practice Pakistan questions with answers and explanations.
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First ionization energy removes the first electron from a neutral gaseous atom.
Successive ionization energies remove additional electrons.
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A cation forms when electrons are lost.
It has more protons than electrons.
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An anion forms when electrons are gained.
It has more electrons than protons.
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Rutherford concluded that atoms contain a small dense positive nucleus.
Most atomic volume is empty space.
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Thomson's cathode-ray experiments revealed negatively charged particles.
He proposed an early model with electrons in positive matter.
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Chadwick identified the neutral nuclear particle in 1932.
Neutrons explain isotopic mass differences.
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Quantum mechanics describes electron probability distributions.
An orbital can hold up to two electrons with opposite spins.
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The Pauli exclusion principle allows two electrons per orbital.
They must have opposite spin quantum numbers.
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An s subshell contains one orbital.
It can hold a maximum of two electrons.
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A p subshell contains three orbitals.
It can hold a maximum of six electrons.
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The mole ratio H2:NH3 is 3:2.
6 mol H2×2/3 = 4 mol NH3.
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Percent yield is actual divided by theoretical times 100.
8/10×100 = 80%.
