Class 12th

A 50 watt bulb emits monochromatic red light of wavelength of 795 nm. The number of photons emitted per second by the bulb is x * 10²⁰. The value of x is________.

[Given: h = 6.63 * 10^-34 Js and c = 3.0 * 10⁸ ms^-1]

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alok kumar singh

Contributor-Level 10

Power = 50 watt = 50 J/sec

Energy emitted per second = 50 J

Wavelength ; $λ$ = 795 nm

Energy of one photon =

$= 0.025 * 1 0^{- 17} J$

Number of photons emitted per second = $\frac{50}{0.025 * 1 0^{- 17}}$

= 2 * 10²⁰

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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: No task is too small—if you want to work "brush teeth" into your daily routine, put it on the list.

Figuring out how to write a daily routine begins by writing down everything you need to get done daily, both at home and at work. (1)____________. Don't worry about how you organize this list; this is a brain dump, not a to-do list. (2)__________. Simply jot down everything you do each day, as well as everything you should get done. (3)__________. If you feel

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Payal Gupta

Contributor-Level 10

The given sentence is talking about some list and also giving an example. Placing the given sentence in 1, 2 and 3 blanks would break the rhythm. Hence, only 4 is the suitable option.

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5 months ago

The major products A and B formed in the following reaction sequence are:

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Vishal Baghel

Contributor-Level 10

Kindly consider the following figure

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Raj Pandey

Contributor-Level 9

The given sentence is talking about some list and also giving an example. Placing the given sentence in 1, 2 and 3 blanks would break the rhythm. Hence, only 4 is the suitable option.

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The four sentences (labelled 1, 2, 3 and 4) below, when properly sequenced, would yield a coherent paragraph. Decide on the proper sequencing of the order of the sentences and choose the correct option.

1. In December, there was a countrywide rainfall deficit of 14 per cent.

2. The northwest, central and east and northeast India were particularly dry with 83 per cent, 77 per cent and 53 per cent deficit in rainfall respectively.

3. The dryness has also continued into January and February, with 27 out of the 36 states and Union territories receiving deficient, large deficient or no rainfall from January 1-February 15, 2023.

4. The peri

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Payal Gupta

Contributor-Level 10

Following the flow of information from December to January, 1243 can be identified the most logical sequence.

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5 months ago

: Answer the questions on the basis of the information given below.

Six friends Amar, Deepu, Manoj, Preet, Rajan and Sahil married within a year in the months of February, April, July, September, November and Decemeber and in the cities of Ahmedabad, Bengaluru, Chennai, Delhi Mumbai and Kolkata, but not necessarily following the above order. The brides' names were Geetika, Jasmine, Hema, Brinda, Ipsita and Veena, once again not following any order. The following aer some facts abnout their weddings.

Manoj's wedding took place in Chennai' however he was not married to Geetika or Veena.

Amar's wedding took place in Ahmedabad and Rajan's

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alok kumar singh

Contributor-Level 10

Friends	Wives	Venue of wedding	Month
Amar	Veena	Ahmedabad	July
Deepu	Geetika	Kolkata	February
Manoj	Ipsita	Chennai	November
Preet	Brinda	Mumbai	December
Rajan	Hema	Delhi	April
Sahil	Jasmine	Benguluru	September

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1. In December, there was a countrywide rainfall deficit of 14 per cent.
2. The northwest, central and east and northeast India were particularly dry with 83 per cent, 77 per cent and 53 per cent deficit in rainfall respectively.
3. The dryness has also continued into January and February, with 27 out of the 36 states and Union territories receiving deficient, large deficient or no rainfall from January 1-February 15, 2023.
4. The period

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Raj Pandey

Contributor-Level 9

Following the flow of information from December to January, 1243 can be identified the most logical sequence.

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5 months ago

1. These remarkable structures are a common sight soaring above the rooftops of Yazd.

2. They are often rectangular towers, but they also appear in circular, square, octagonal and other ornate shapes.

3. Among Yazd's ancient technologies is the wind catcher, or bâdgir in Persian.

4. The city of Yazd in the desert of central Iran has long been a focal point for creative ingenuity.

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Payal Gupta

Contributor-Level 10

Sentence 4 introduces the city of Yazd and 1 further elaborates the 4^th sentence. 4132 is the most logical sequence.

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5 months ago

Match List-I with List-II.

List – I List – II

(Metal ion)

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Vishal Baghel

Contributor-Level 10

$M n^{+ 2} \to g r o u p I V (M n^{+ 2}, C o^{+ 2}, Z n^{+ 2}, N i^{2 +})$

$A s^{+ 3} \to g r o u p I I B (A s^{+ 3}, A s^{+ 5}, S b^{+ 3}, S b^{+ 5}, S n^{+ 2}, S n^{+ 4})$

$\begin{array}{l} C u^{+ 2} \to g r o u p I I A (C u^{+ 2}, P b^{+ 2}, H g^{+ 2}, C d^{+ 2}, B i^{+ 3}) \\ A l^{+ 3} \to g r o u p I I I (F e^{+ 3}, A l^{+ 3}, C r^{+ 3}) \end{array}$

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5 months ago