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Class 12th English

Four jumbled up sentences, related to a topic, are given below. Three of them can be put together to form a coherent paragraph. Identify the odd one out.

1. Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation.

2. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby.

3. If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion.

4. When a star burns through the last of its fuel, the object may collapse, or fall into it

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Raj Pandey

Contributor-Level 9

1, 2 and 3 talks about a black hole and its distinctive features. However, 4^th sentence talks about a star and its life.

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Class 12th Chemistry

Which one of the following 0.06M aqueous solutions has lowest freezing point?

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alok kumar singh

Contributor-Level 10

Depression in freezing point will be maximum for Al₂ (SO₄)₃ since its Van't Hoff factor is the highest. So its solution will have the lowest freezing point.

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Class 12th Maths

Let in a right angled triangle, the smallest angle be θ. If a triangle formed by taking the reciprocal of its sides is also a right angled triangle, then sinθ is equal to:

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Vishal Baghel

Contributor-Level 10

Let the smallest angle is C =?

Therefore angle A = 90° -?

And angle B = 90°

i.e. b > a > c

Here, a = 2 R cos? , b = 2R, c = 2R sin?

b² = a² + c²

according to question,

$\begin{array}{l} \frac{1}{c^{2}} = \frac{1}{a^{2}} + \frac{1}{b^{2}} \\ ? \frac{a^{2} b^{2}}{c^{2}} = a^{2} + b^{2} \end{array}$

=> $s i n ? = ? \frac{\sqrt[]{5} ? 1}{2}$

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8 months ago

Class 12th Maths

If [x] denotes the greatest integer less than or equal to x, then the value of the integral $\int_{- π / 2}^{π / 2} [[x] - s i n x] d x$ is equal to:

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Vishal Baghel

Contributor-Level 10

$l = \int_{- \frac{π}{2}}^{\frac{π}{2}} ([x] + [- s i n x]) d x$ . (i)

$I = \int_{- \frac{π}{2}}^{\frac{π}{2}} ([- x] + [s i n x]) d x$ . (ii)

by using property $(\int_{a}^{b} f (x) d x = \int_{a}^{b} f (a + b - x) d x)$

Adding (i) and (ii) we get 2l = $\int_{- \frac{π}{2}}^{\frac{π}{2}} (- 2) d x = - 2 π \Rightarrow l = - π$

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8 months ago

Class 12th Chemistry

When silver nitrate solution is added to potassium iodide solution then the sol produced is:

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alok kumar singh

Contributor-Level 10

When AgNO₃ is added to Kl solution, precipitate of Agl is formed which adsorb I^- ion from

Dispersion medium to give negatively charged sol

$A g N O_{3} + K l \to A g l ↓ + K N O_{3}$

Agl/l^-- negatively charged sol.

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8 months ago

Class 12th Matrices

If sum of the first 21 terms of the series $l o g_{9^{\frac{1}{2}}} x + l o g_{9^{\frac{1}{3}}} x + l o g_{9^{\frac{1}{4}}} x + . . . .,$ where x > 0 is 504, then x is equal to:

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Vishal Baghel

Contributor-Level 10

$l o g_{9^{\frac{1}{2}}} x + l o g_{9^{\frac{1}{3}}} x + l o g_{9^{\frac{1}{4}}} x + . . . . . . . + l o g_{9^{\frac{1}{22}}} x = 504$

=> $2 l o g_{9} x + 3 l o g_{9} x + 4 l o g_{9} x + . . . . . . . . + 22 l o g_{9} x = 504$

=> (1 + 2 + 3 + .+ 22) log₉ x – log₉ x = 504 Þ x = 81

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8 months ago

Class 12th English

The passage below is accompanied by a set of questions. Choose the best answer to each question.

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The passage below is accompanied by a set of questions. Choose the best answer to each question.

Tens of thousands of years ago, a huge horse species walked, trotted and galloped across the shifting sands of what is today South Africa's Cape south coast.
The Giant Cape Zebra (Equus capensis) weighed an estimated 450 kg. Its extant relatives in southern Africa are far smaller: the plains zebra weighs between 250 and 300 kg and the Cape mountain zebra is the smallest of all zebra species, with a mass of between 230 and 260 kg.
The Giant Cape Zebra became extinct just over 10,000 years ago. This may have been partly because of the loss of its preferred habitat of extensive grasslands, as rising sea levels flooded the vast Palaeo-Agulhas Plain. But until now it hasn't been clear how common the species was on the Cape south coast because its body fossils are predominantly from southern Africa's west coast.
That's where ichnology – the study of tracks and traces – comes in. Since 2007 our team has documented more than 350 fossil vertebrate tracksites along a 350 km stretch of the Cape south coast.
Now, by studying the tracks left by those galloping, walking and trotting zebra so long ago, we're able to say that they must have been a fairly regular sight on the landscape of the Cape south coast, and were more common than was suggested by the body fossil record in the area. This confirms the capacity of the body fossil record and ichnology to complement each other.
Being able to look back in time in this way doesn't just help scientists to better understand ancient landscapes. It's also an important part of understanding what's changed over time and the effects of climate change and humans.
In our recently published article, we described how we have identified 26 equid tracksites – including tracks belonging to Equus capensis – in aeolianites (cemented dunes) on South Africa's Cape south coast in the vicinity of towns like Still Bay and Plettenberg Bay.
This is especially exciting because equid tracks dating to the Pleistocene epoch, which started 2.6 million years ago and ended about 11,700 years ago, are rare. In fact, our finds mean that the Cape south coast accounts for the majority of the sites known globally from this time period (other sites are in Kenya, Ethiopia, Italy, the Arabian Peninsula, and the Americas).
Thirteen of the tracksites we found contain tracks 12 cm or greater in length, and eight contain tracks 10 cm or less in length (in the remaining five cases we could not access the tracks for measurement). Well preserved equid tracks are fairly distinctive: features include an unbroken hoof wall and what is known as a “frog” towards the centre of the track.

Which of the following statements is NOT correct according to the passage?

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