Correct Answer: B. equal to marginal

Explanation

(a)(i) Emission line spectra consist of distinct and separate bright lines of definite wavelengths on a dark background.

Any valid additional information e.g

- They are obtained when light from a luminous source undergoes dispersion and is observed directly.

- When an electron moves from one energy level to another energy level, line spectra are observed

- The colour of the spectra is a characteristic of the source.

(ii) Line absorption spectra are obtained when light passes through a cool gas and certain wavelengths of the light are absorbed. This gives series of dark lines, each corresponding to one of the wavelengths absorbed.

(b) Diagram

When radiation of appropriate frequency falls on the cathode (with photosensitive surface) electrons are emitted. Because the anode is positive with respect to the cathode, the electrons are attracted to the anode. The electrons flow completes the circuit and current flows.

(c)(i) Wave properties of X-rays

- diffraction

- interference

- reflection

- refraction

- polarization

(ii) Uses of X-rays other than in medicine

1. to study crystal structures
2. to detect presence of cracks in welded parts
3. in artistic works for determining the authenticity of such works
4. at security check points to scan
5. X-ray spectroscopy for identifying isotopes of elements.

Correct Answer: C. y > 4

Explanation

\((Y-3)<\frac{y}{3}\\

3y - 9< y\\

2y< 9\\

y< 4\frac{1}{2}\)

Correct Answer: B. existing general reserve

Correct Answer: C. electrovalent compound

Explanation

The correct answer is C. electrovalent compound.

Electrovalent (ionic) compounds are held together by strong electrostatic forces of attraction between oppositely charged ions arranged in a regular crystal lattice. A large amount of thermal energy is required to break these strong bonds, which gives them characteristically high melting and boiling points.

In contrast, simple covalent compounds are held by weak intermolecular forces and generally have low melting and boiling points.

Correct Answer: C. ∆H< T ∆S

Explanation

The correct answer is C. ∆H< T ∆S.

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The spontaneity of a reaction at constant temperature and pressure is determined by the Gibbs free energy change (\Delta G):

\Delta G = \Delta H - T\Delta S

For a reaction to occur spontaneously, the change in Gibbs free energy must be negative (\Delta G< 0):

\Delta H - T\Delta S< 0

\Delta H< T\Delta S

• A. \Delta G = 0: The system is at equilibrium.

• B. \Delta S< 0 and \Delta H > 0: The reaction is non-spontaneous at all temperatures (\Delta G > 0).

• D. \Delta G > 0: The reaction is non-spontaneous.

Correct Answer: C. poverty

Correct Answer: B. increasing

Correct Answer: C. N80,000

Correct Answer: (c) ‘miscellaneous and maintenance’

Explanation

The correct answer is (c) ‘miscellaneous and maintenance’.

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• Miscellaneous is spelled with a single 'c', double 'l', and ends in *-eous*.

• Maintenance retains the *-ten-* root (from *maintain* changing its vowel sound) and ends in *-ance*, not *-ainance*.