In the following questions a statement of assertion (A) is followed by a statement of reason ( R).
A : Horizontal metion of projectile without effect of air is uniform motion.
R : Without air effect the horizontal acceleration of projectile is zero .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion then mark (1) .
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion then mark (2)
C. If Assertion is true statement but Reason is false then mark (3).
D. If both Assertion and Reason are false statements then mark (4) .

Answer

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step 1: Understand the Assertion
The assertion states that "the horizontal motion of a projectile without the effect of air is uniform motion."

**Explanation:**
In projectile motion, when we neglect air resistance, the only force acting on the projectile is gravity, which acts vertically downward. The horizontal component of motion does not experience any horizontal force, thus it moves with a constant velocity.

### Step 2: Understand the Reason
The reason states that "without air effect, the horizontal acceleration of the projectile is zero."

**Explanation:**
Since there are no horizontal forces acting on the projectile (due to the absence of air resistance), the horizontal acceleration is indeed zero. According to Newton's first law, if no net external force acts on an object, it will maintain its state of motion, which means it will continue to move with constant velocity.

### Step 3: Connect Assertion and Reason
Now, we need to see if the reason correctly explains the assertion.

**Explanation:**
The assertion is true because the horizontal motion is uniform, and the reason is also true because the horizontal acceleration is zero. The reason correctly explains why the horizontal motion is uniform: because there is no acceleration acting on the projectile in the horizontal direction.

### Conclusion
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

**Final Answer:**
Assertion (A) is true, Reason (R) is true, and R is the correct explanation of A.