Explanation

 A ray of light represents the direction of propagation of the wave.

A wavefront is a surface over which the phase of the wave is constant.

Rays are always perpendicular to the wavefronts.

Explanation

When a coin is tossed once, the possible outcomes are Head (H) or Tail (T).

The sample space is the set of all possible outcomes: {H, T}.

Explanation

The first moment about the mean measures the average deviation from the mean, which is always zero.

This is because the sum of deviations from the mean cancels out.

Explanation

Calcium (Ca) typically has an oxidation number of +2.

Oxygen (O) typically has an oxidation number of -2.

In the chlorite ion (ClO2-), let the oxidation number of Cl be 'x'.

The total charge of the chlorite ion is -1.

So, the equation becomes: x + 2*(-2) = -1

Solving for x: x - 4 = -1, therefore x = +3

Since there are two chlorite ions in the compound, the overall oxidation number of Cl in Ca(ClO2)2 is +3.

Explanation

The average daily human energy intake is roughly 2000-2500 kilocalories.

One liter of petrol contains approximately 34.2 Megajoules (MJ) of energy, equivalent to roughly 8342 kilocalories.

Therefore, 1/4 liter of petrol has about 8.55 MJ of energy, which is closer to the daily human energy needs than the other options. 

Explanation

The electric field due to a positive charge points away from the charge, i.e., radially outward.

Field lines show the direction a positive test charge would move.

Explanation

The trichotomy property specifically applies to inequalities, stating that for any two real numbers, exactly one of three possibilities must be true:

The first number is less than the second, the first number is greater than the second, or the two numbers are equal. 

Explanation

 In aromatic sulfonation, sulfur trioxide (SO3) is the actual attacking species, reacting with the aromatic ring to form a sulfonic acid. 

Explanation

CONVEY (اظہار کرنا / پہنچانا)

Communicate (ابلاغ کرنا / بات چیت کرنا)

Explanation

The pea plant (Pisum sativum) has 7 pairs of homologous chromosomes, i.e., 14 chromosomes in total.

This was the organism used by Gregor Mendel in his foundational genetics experiments.