Explanation

"She is worried about her exams". 

When expressing concern or anxiety about something, the correct preposition to use with "worried" is "about". 

Explanation

 Protons are present in the nucleus of every atom, including hydrogen, which has 1 proton and no neutron in its most common isotope.

Neutrons are present in most nuclei except ordinary hydrogen (¹H).

Electrons are found in the electron cloud, outside the nucleus.

Positrons are antimatter particles, not normally found in atomic nuclei.

Explanation

The correct phrase is "intrigued against someone", which means to plot secretly or scheme against that person.

He intrigued against his master.

Explanation

120° = 120 × π/180 = 2π/3.

Explanation

The time period of a simple pendulum is independent of its mass.

It depends on length and acceleration due to gravity:

T = 2π√L/g

Explanation

Explanation

"He heard him sing a song."

Verbs like "hear, see, watch, feel" are followed by the bare infinitive (i.e., the base form of the verb without "to") when used in the active voice.

So, "heard him sing" is correct, not "to sing" or "sang."

Explanation

Explanation

Explanation

Use the Gibbs free energy equation:

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

For a process to be spontaneous, $Delta G < 0$

• If $Delta H < 0$ (exothermic)

• And $Delta S > 0$ (entropy increases)

• Then:

  $$\Delta G=\text{negative}-T\times \text{positive}=\text{always negative}$$

 So, no matter the temperature, $Delta G$ will be negative ⇒ spontaneous at all temperatures