$
d = 3.84 \times 10^5 \text{ km}
$

A substance which does not allow current to pass through is
\begin{enumerate}[label=(\roman)]
\item Conductor
\item Semiconductor
\item Insulator
\item None of the above
\end{enumerate}

The atomic number is the number of
\begin{enumerate}[label=(\roman
)]
\item Protons
\item Neutrons
\item Electrons
\item Molecules
\end{enumerate}

Fill in the blanks:
\begin{enumerate}
\item Acceleration due to gravity on the earth is [tex]$\qquad$[/tex]
\item Audible range of the human ear is [tex]$\qquad$[/tex]
\item Speed of light in vacuum is [tex]$\qquad$[/tex]
\item Dimensions of work are [tex]$\qquad$[/tex]
\item Rate of change of velocity is [tex]$\qquad$[/tex]
\item The substance which reflects light is called [tex]$\qquad$[/tex]
\end{enumerate}



Answer :

Let's systematically address each part of the problem:

### 1. Substance that does not allow current to pass through
A substance that does not allow current to pass through is called:
- (i) Conductor
- (ii) Semiconductor
- (iii) Insulator
- (iv) Other (que)

Answer: (iii) Insulator

### 2. Atomic number definition
The atomic number is the number of:
- (i) Protons
- (ii) Neutrons
- (iii) Electrons
- (iv) Moles

Answer: (i) Protons

### 3. Fill in the blanks
Let's fill in each blank based on standard scientific knowledge.

- Acceleration due to gravity on the Earth: The standard acceleration due to gravity on Earth, denoted by \( g \), is 9.8 m/s².

- Audible range of the human ear: The human ear can typically hear sounds in the frequency range of 20 Hz to 20,000 Hz (20 kHz).

- Speed of light in vacuum: The speed of light in a vacuum is approximately 299,792 km/s (approx. 300,000 km/s).

- Dimensions of work: Work is defined as force applied over a distance. Its dimensions in terms of base units are [M¹ L² T⁻²].

- Rate of change of velocity: The rate of change of velocity is known as acceleration.

- Substance which reflects light: A substance that reflects light is typically called a mirror or reflective surface.

Thus, the filled blanks will look like this:
1. Acceleration due to gravity on the earth: 9.8 m/s²
2. Audible range of human ear: 20 Hz to 20,000 Hz
3. Speed of light in vacuum: 299,792 km/s
4. Dimensions of work: [M¹ L² T⁻²]
5. Rate of change of Velocity: Acceleration
6. The substance which reflects light is called: Mirror or reflective surface