Class 12th

Contributor-Level 10

$h ν = 3.4 - 1.51 = 1.89 e V$

As we know that radius of circular path in magnetic field is given as

$r = \frac{\sqrt[]{2 m K}}{q B} \Rightarrow K = \frac{r^{2} q^{2} B^{2}}{2 m}$

$\Rightarrow K = \frac{{(7 * 1 0^{- 3})}^{2} * (1.6 * 1 0^{- 19}) * {(5 * 1 0^{- 4})}^{2}}{2 * 9.1 * 1 0^{- 31}} e V = 107.7 * 1 0^{- 2} e V$ = 1.08 eV

$\Rightarrow ? = h ν - K = 1.89 - 1.08 = 0.81 e V$

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New answer posted

a year ago

There is a sentence that is missing in the paragraph below. Look at the paragraph and decide in which blank (option 1, 2, 3, or 4) the following sentence would best fit.

Sentence: Therefore, over time, there will be more copies of these mutants than other molecules.

(1)____________.The “RNA world” hypothesis suggests that early life may have used RNA as material for both genes and replication before the emergence of DNA and proteins. (2)___________. Once an information system can make copies of itself, natural selection kicks in. (3)_________. Some of the new copies of these molecules (which some would call “genes”) will

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Contributor-Level 10

The given sentence concludes the statement given before the 4^th blank. Hence, it meaningfully fits in the 4^th blank only.

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a year ago

Class 12th Physics

The value of current in the $6 Ω$ resistance is:

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Contributor-Level 10

Method-I : Using Kirchhoff's Law for loop $\vec{B D A B B},$ we can write

$- 140 + 20 l + 6 l_{1} = 0 \Rightarrow 10 l + 3 l_{1} = 70 . . . . . . . (i)$

Using Kirchhoff's Law for loop $\vec{A C B B A},$

we can write

$5 (l - l_{1}) + 90 - 6 l_{1} = 0$

->-5l + 11l₁ = 90 .(ii)

Adding equation (1) with twice the equation (2), we have

$25 l_{1} = 250 \Rightarrow l_{1} = \frac{250}{25} = 10 A$

Method-II : Using concept of equivalent cell, we can write

$V_{A B} = \frac{\frac{140}{20} + \frac{0}{6} + \frac{90}{5}}{\frac{1}{20} + \frac{1}{6} + \frac{1}{5}} = \frac{2100 + 0 + 5400}{15 + 50 + 60}$

$= \frac{7500}{125} = 60 V o l t$

$\Rightarrow l_{1} = \frac{60}{6} = 10 A$

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New answer posted

a year ago

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. There is a huge range of electronic options as well as the traditional paper-based route.

2. It provides an opportunity to explore multiple topics and ideas.

3. You could, for example, use a diary app such as Penzu, which claims to take security very seriously, try a note-taking app like Google Keep, or just record your thoughts in a Word document stored on your laptop or in the cloud.

4. You could even go 'open' and keep a blog, sharing your thoughts with the world, and not just y

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Can I apply for supplementary exams of CBSE class 12th for 3 subjects?

Contributor-Level 10

Here, 1, 3 and 4 seem to be talking about diary writing and methods that can be adopted to do the same. 2 seems odd here.

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New answer posted

a year ago

Class 12th CBSE

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Prabhjot Singh

Beginner-Level 5

No you can't apply for 3 supplementary exam because CBSE allow only for 2 subjects

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New answer posted

a year ago

Class 12th Physics Nuclei

A radioactive material decays by simultaneous emissions of two particles with half lives of 1400 years and 700 years respectively. What will be the time after which one third of the material remains? (Take In 3 = 1.1)

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Contributor-Level 10

As we know that equivalent half life of radioactive material decays by simultaneous emissions, is given as

$\frac{1}{T} = \frac{1}{T_{1}} + \frac{1}{T_{2}} = \frac{1}{700} + \frac{1}{1400} = \frac{3}{1400} \Rightarrow T = \frac{1400}{3} y e a r s$

$\Rightarrow t = \frac{l n (3)}{λ} = \frac{l n (3)}{l n (2)} T = \frac{1.1}{0.693} * \frac{1400}{3} \approx 740.74 y e a r s$

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New answer posted

a year ago

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. If you have more words at your order, you have a fat bank, words in abundance. You can do well in writing as well as speaking and be notably better than the trench of humankind.
2. The English, though hybrid, is an intriguing amalgamation of different dialects. It openly acquires from every other language of the world.
3. Words in the hands of a magician of vocabulary have warmth, colour and variety which express human feelings that lie buried in layers of the mind.
4. They are the m

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Contributor-Level 10

Other than 4^th, all the sentences talk about problems associated with water usage.

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New answer posted

a year ago

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.

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Contributor-Level 10

The second sentence talks about the English language while the rest talk about the power of words.

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New answer posted

a year ago

Class 12th Physics Nuclei

A nucleus of mass M emits $γ -$ rays photon of frequency 'v'. The loss of internal energy by the nucleus is : [Take 'c' as the speed of electromagnetic wave]

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Contributor-Level 10

Using conservation linear momentum, we can write

$M v = \frac{h}{λ} = \frac{h ν}{c} \Rightarrow v = \frac{h ν}{M c}$

Loss of internal energy = Gain in Kinetic energy + energy of gamma ray

= $\frac{1}{2} M v^{2} + h ν = \frac{1}{2} M {(\frac{h ν}{M c})}^{2} + h ν = h ν [1 + \frac{h ν}{2 M c^{2}}]$

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New answer posted

a year ago

The passage given below is followed by four alternate summaries. Choose the option that best captures the essence of the passage.

Around 1118, a French knight named Hugues de Payens created a military order along with eight relatives and acquaintances that became the Knights Templar, and they won the eventual support of the pope and a reputation for being fearsome fighters. The Fall of Acre in 1291 marked the destruction of the last remaining Crusader refuge in the Holy Land, and Pope Clement V dissolved the Knights Templar in 1312.

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