Explanation

(a) If a stable element is bombarded by \(\alpha\) - particles the nucleus will become unstable and decay into other elements with the release of energy.

Example; \(^{14}_{7}N + ^4_2He \to ^{17}_8 O + ^1_1H\) + Energy

(b) When the nucleus of Uranium is bombarded with a neutron, it splits into two nearly equal parts with a release of energy and neutrons. These excess neutron, if not controlled, further bombard the remaining nuclei, causing a chain reaction and consequently an explosion, provided the critical mass of the Uranium is, exceeded

\(^{235}_{92}U + ^1_0U \to ^{236}_{92}U \to ^{141}_{56}Ba + ^{92}_{36}Kr + 3^1_0n\) + Energy

(c)(i) Radioactive substances give off identifiable radiation i.e \(\alpha, \beta\) and 8 radiations

(ii) They are chemically identical to their non-radioactive counterparts and later can be made radioactive by bombardment with nuclear particles

(iii) Radioactive materials decay with specific half-life.

(d) Three applications of atomic energy

(i) It is used for the production of nuclear weapons for warfare

(ii) It is used in the generation of electric power

(iii) It is used to detect leakages in underground pipes carrying oil or gases.

(e) Two Postulates of Bohr's Model of the Atom:

(i) Electrons occupy certain fixed orbits around the nucleus of an atom. When an electron is in one of these orbits it does not radiate any energy

(ii) The angular momentum is quantized in the allowed orbit.

Two Limitations To Bohr's Model:

(i) It could not interpret the details of the spectra of complex atoms

(ii) There is no theoretical basis for selecting the allowed orbits postulated.

Correct Answer: C. Cockroach

Explanation

Most insects show parental care to their offspring.

Correct Answer: D. is demanded because of what it can help to produce

Correct Answer: D. quatrain

Explanation

The third stanza of the Shakespearean sonnet is a quatrain. A Shakespearean sonnet consists of three quatrains (four lines each) and a final rhymed couplet. The quatrain presents a separate idea or example, and the couplet provides a summary or a different take on the previous lines.

Explanation

(a)

Given: Circle ABC with centre O

To prove : < AOB = 2 < ACB

Construction: Join CO produced to P.

Proof: With lettering as in the figure,

OA = OB (radii) ; \(x_{1} = x_{2}\) (base angles of an isosceles triangle)

\(\therefore < AOP = x_{1} + x_{2}\) (exterior angle of triangle AOC)

\(\therefore < AOP = 2x_{2} (x_{1} = x_{2})\)

Also, \(< BOP = 2y_{2}\) (similar proof as the earlier done ones)

\(\therefore < AOB = 2x_{2} + 2y_{2} = 2(x_{2} + y_{2})\)

\(< AOB = 2 \times < ABC\) (proven)

(b) From the diagram, < OQR = 32° and < MPQ = 15°.

(i) \(\therefore < ORQ = 32°\) (base angles of an isosceles triangle)

\(< OQR = 180° - (32° + 32°) = 180° - 64° = 116°\)

\(\therefore < QPR = \frac{116°}{2} = 58°\) (angle subtended at the centre)

(ii) Join MO and MQ,

Since < MPQ = 15°

then < MOQ = 2 < MPQ (angle at the centre)

\(\therefore < MOQ = 2 \times 15° = 30°\)

\(\therefore < OMQ = < MQO \) (base angles of an isosceles triangle)

\(\therefore < MQO = \frac{180° - 30°}{2} = 75°\)

Correct Answer: D.θ = 218\(^o\), 323\(^o\)

Explanation

On the \(y\)-axis, each box is \(\frac{1 - 0}{5} = \frac{1}{5}\) = 0.2unit

On the \(x\)-axis, each box is \(\frac{90 - 0}{6} = \frac{90}{6} = 15^o\)

⇒ \(θ_1 = 180^o + (2.5\times15^o) = 180^o + 37.5^o = 217.5^o ? 218^o \)(2 and half boxes were counted to the right of 180\(^o\))

⇒ \(θ_2 = 270^o + (3.5\times15^o) = 270^o + 52.5^o = 322.5^o ? 323^o \)(3 and half boxes were counted to the right of 270\(^o\))

∴ \(θ = 218^o, 323^o\)

Correct Answer: C. an eptgram

Correct Answer: B. The kidney

Correct Answer: A. Customer satisfaction

Correct Answer: D. 4m/s