Explanation

The correct sentence is: "Sarah looked at herself in the mirror before leaving."

"Herself" is the appropriate reflexive pronoun used when the subject and object are the same person.

Explanation

Polio primarily affects the nervous system and can cause muscle weakness or paralysis.

It often targets children and may lead to permanent disability.

Explanation

Sets that have the same number of elements (cardinality) are called equivalent sets.

They may have different elements but the same total count.

Explanation

Temperature differences across the Earth, due to sunlight angle and duration.

They are a major factor in creating different climates.

These variations influence air pressure, precipitation, and seasonal patterns, shaping climate zones.

Explanation

The head of a chlorophyll molecule contains a porphyrin ring with a central magnesium (Mg) atom.

This ring has four nitrogen atoms that coordinate with the magnesium, forming a stable complex essential for photosynthesis.

Explanation

In HNO₃ (nitric acid):

Hydrogen (H) = +1

Oxygen (O) = -2 (×3 = -6)

Let nitrogen = x

So, +1 + x + (−6) = 0

⇒ x = +5

Nitrogen has an oxidation state of +5 in HNO₃.

Explanation

Jinnah highlighted civilization, literature, and art and architecture as key elements of Muslim identity in his speeches.

Armed forces were not specifically mentioned by him as part of Muslim identity in this context.

Explanation

Given xy = 1 and x > 0:

y = 1/x

We want to minimize x + y = x + 1/x.

Let's find the minimum value:

Let f(x) = x + 1/x

f'(x) = 1 - 1/x² = 0 for minimum

x² = 1

x = 1 (since x > 0)

f(1) = 1 + 1/1 = 2

The minimum value of x + y is 2.

Explanation

Evaluation is a key component of curriculum as it assesses the effectiveness of teaching and learning.

It helps in determining whether educational goals and objectives are being met.

Explanation

Gravitational force (F) is given by:

F ∝ (m1 * m2) / r²

If both masses (m1 and m2) are halved:

New force F' ∝ ((m1/2) * (m2/2)) / r²

F' ∝ (m1 * m2) / (4 * r²)

F' = F / 4

The gravitational force becomes one fourth.