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All questions of CBSE New Pattern: Term II Practice Questions for JEE Exam

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इनमें से कौन-सा क्षेत्र प्रागैतिहासिक शैल कला चित्रों की मेजबानी के लिए प्रसिद्ध हैं?
1. मध्य प्रदेश की विंध्य पर्वतमाला
2. उत्तर प्रदेश का कैमूरियन विस्तार
उपरोक्त में से कौन सा/से सही हैं?
  • a)
    केवल 1
  • b)
    केवल 2
  • c)
    दोनों 1 और 2
  • d)
    इनमे से कोई भी नहीं
Correct answer is option 'C'. Can you explain this answer?

Amit Sharma answered
  • मध्य प्रदेश के विंध्य पर्वतमाला और उत्तर प्रदेश में उनके कैमूरियन विस्तार से सबसे समृद्ध चित्रों की सूचना मिली है। ये पर्वत श्रृंखलाएं पुरापाषाण और मध्यपाषाणकालीन अवशेषों से परिपूर्ण हैं। 9000 ईसा पूर्व में पाषाण युग की संस्कृति में एक मध्यवर्ती चरण शुरू हुआ, जिसे मेसोलिथिक युग कहा जाता है।
  • मध्य प्रदेश, उत्तर प्रदेश, आंध्र प्रदेश, कामतका और बिहार के कई जिलों की गुफाओं में शैल चित्रों के अवशेष हैं।
  • उत्तराखंड में कुमाऊं की पहाड़ियां भी शैल चित्रों के लिए जानी जाती हैं।

Direction: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as
Assertion (A): P is a point on the line segment joining the points (3, 2, –1) and (6, –4, –2). If x coordinate of P is 5, then its y coordinate is –2.
Reason (R): The two lines x = ay + b, z = cy + d and x = a’y + b’, z = c’y + d’ will be perpendicular, iff aa’ + bb’ + cc’ = 0.
  • a)
    Both A and R are true and R is the correct explanation of A
  • b)
    Both A and R are true but R is NOT the correct explanation of A
  • c)
    A is true but R is false
  • d)
    A is false but R is True
Correct answer is option 'C'. Can you explain this answer?

Shalini Bose answered
Assertion (A): P is a point on the line segment joining the points (3, 2, –1) and (6, –4, –2). If x coordinate of P is 5, then its y coordinate is –2.

Reason (R): The two lines x = ay b, z = cy d and x = a’y b’, z = c’y d’ will be perpendicular, iff aa’ bb’ cc’ = 0.

The given assertion relates to the coordinates of a point P on a line segment joining two given points. The reason provided relates to the condition for two lines to be perpendicular.

Explanation:

To understand this assertion and reason, let's first find the equation of the line segment joining the points (3, 2, –1) and (6, –4, –2).

The equation of a line segment joining two points (x₁, y₁, z₁) and (x₂, y₂, z₂) can be written as:
(x - x₁)/(x₂ - x₁) = (y - y₁)/(y₂ - y₁) = (z - z₁)/(z₂ - z₁)

Plugging in the given values, we have:
(x - 3)/(6 - 3) = (y - 2)/(-4 - 2) = (z + 1)/(-2 - (-1))

Simplifying, we get:
(x - 3)/3 = (y - 2)/(-6) = (z + 1)/(-1)

Now, let's consider the x-coordinate of P as 5. Substituting this value into the equation, we get:
(5 - 3)/3 = (y - 2)/(-6) = (z + 1)/(-1)

2/3 = (y - 2)/(-6) = (z + 1)/(-1)

Simplifying further, we get:
(y - 2)/(-6) = (z + 1)/(-1)

Cross-multiplying, we get:
-6(y - 2) = -1(z + 1)

Expanding, we get:
-6y + 12 = -z - 1

Rearranging, we get:
z = -6y + 13

Comparing this equation with the given equations:
x = ay + b
z = cy + d

We can see that a = 0, b = 0, c = -6, and d = 13.

Now, let's consider the given reason. According to the reason, the two lines x = ay + b, z = cy + d and x = a'y + b', z = c'y + d' will be perpendicular if aa' + bb' + cc' = 0.

Plugging in the values, we have:
(0)(0) + (0)(0) + (-6)(0) = 0

Therefore, aa' + bb' + cc' = 0, which means the two lines are perpendicular.

Therefore, both the assertion and the reason are true, and the reason correctly explains the assertion.

Hence, the correct answer is option C.

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