Answer: Option A. ->
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(a) Answer: 1 Mark
     Example along with diagram: 1 Mark
(b) Definition: 1 Mark
(c) Answer: 1 Mark
(a) If it happens for ${120}^{\circ }$, it will also happen for multiples of ${120}^{\circ }$, such as ${240}^{\circ }$ and ${360}^{\circ }$.
The example is an equilateral triangle.

(b) The number of position in which the object looks exactly the same is called the order of rotational symmetry.
(c) The order of rotational symmetry of a semicircle is $1$.

Answer: Option A. ->
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Each option: 2 Marks
(a) The asked diagram is a pentagon.

(b)  A polygon with adjacent sides equal and perpendicular is a square. A square has 4 lines of symmetry.

Answer: Option A. ->
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Correct name: 1 Mark
Diagram: 1 Mark
Formula for area: 1 Mark
Result: 1 Mark
A general parallelogram is a geometric figure which does not have any line of symmetry. It, however, has an order of rotational symmetry of 2 as we get the same figure when it's rotated by ${180}^{\circ }$ or ${360}^{\circ }$.
For example, if we rotate the following figure by ${180}^{\circ }$, we will still get an identical figure, hence it has an order of rotational symmetry as 2.

For a parallelogram, the area is given by  Base x Height
According to question, Base = 6m and Height = 4m
Area = $6\times 4=24m^2$

Answer: Option A. ->
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Figures with order of symmetry 4: 1 Mark
Figures with order of symmetry 3: 1 Mark
Figures with order of symmetry 2: 1 Mark
Figures with order of symmetry 1: 1 Mark
Figures (a) and (f) will look the same if rotated by 90${}^o$, 180${}^o$, 270${}^o$ or 360${}^o$. Hence, they have an order of 4.
Figures (b) and (e) will look the same if rotated by 120${}^o$, 240${}^o$ or 360${}^o$. Their order of rotational symmetry will thus be 3.
If we rotate figure (d) by 180${}^o$ or 360${}^o$, we will get the same figure. Hence, it has an order of 2.
But option (c) has an order of only 1 since the same figure can be obtained if the figure is rotated by 360${}^o$.

Answer: Option A. ->
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(i) Answer: 2 Marks
(ii) Answer: 2 Marks
a) Vertical mirror – A, H, I, M, O, T, U, V, W, X and Y

Horizontal mirror - B, C, D, E, H, I, O and X

(ii)  If a figure can be folded along any line such that one half superimposes or aligns exactly with the other, it is known as a symmetric figure. For e.g. If you take a square and fold it across the line shown, part 1 exactly overlaps on part 2. So, the square is a symmetric figure.

On the other hand, in a parallelogram, the diagonal divides it into two congruent triangles (can be proven using SSS congruence condition), i.e. into two equal parts. But those parts don’t superimpose each other when folded across diagonal (as shown in the figure). So, the parallelogram is not symmetric.

    

Hence, Suraj is right and Ravi is wrong.

Answer: Option A. ->
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Two lines of symmetry are possible for a rectangle.

 

Answer: Option A. ->
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Correct Answer: 1 Mark
Diagram: 1 Mark
A parallelogram has 0 lines of symmetry.

Answer: Option A. ->
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Statement: 1 Marks​​​​​​
Reason: 1 Mark
The statement is not correct because $\frac{360}{17}$ is not a natural number, a figure can not have an angle of rotation as ${17}^{\circ }$.

Answer: Option A. ->
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Process: 2 Marks
Result: 1 Mark
The given polygon is square.

Perimeter 4a = 92

                a = 23 m

 Area = $a^2$ = 529 $m^2$

Hence the above polygon is a square and a square has 4 lines of symmetry. 

Answer: Option A. ->
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Answer: 1 Mark
Reason: 1 Mark
Among the following letters only  A, H and V have vertical symmetry.
A, H and V  will look identical if we look at their images formed by a vertical mirror but the rest of the given letters won't.