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Class 12th Chemistry

Among the following compounds I-IV, which one forms a yellow precipitate on reacting sequentially with (i) NaOH (ii) dil. HNO₃ (iii) AgNO₃?

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Vishal Baghel

Contributor-Level 10

Yellow precipitate is Agl (s) which only produce by structure IV

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8 months ago

Class 12th English

There are 6 refineries, 7 depots, 9 districts. The refineries are R1, R2, R3, R4, R5, R6. The depots are D1, D2, D3, D4, D5, D6 and D7 and the districts are DR1, DR2, DR3, DR4, DR5, DR6, DR7, DR8, DR9.

Table A shows the cost of transporting one unit from refinery to depot.

Table B shows the cost of transporting one unit from depot to districts.

Table - A
	R1	R2	R3	R4	R5	R6
D1	928.2	537.2	567.8	589.9	800.1	323.4
D2	311.8	595.7	885.7	759.9	793.1	420.1
D3	451.1	0	320.1	720.1	1000.1	404.5
D4	371.1	50.1	350.1	650.4	980.1	525.3
D5	1137.3	314.5	0	1157.7	406.3	617.5
D6	617.1	516.8	756.5	1065.9	623.9	509.4
D7	644.3	299.2	537.2	1093.1	725.8	827.4

Table - B
	D1	D2	D3	D4	D5	D6	D7
DR1	571.1	205	352	159	434.5	178	337
DR2	200	337.5	291	201	0	980.7	434
DR3	100	0	275	277	850	770.5	835
DR4	0	415.7	350	760	300	560	444.7
DR5	223.5	300	440	1033	880	325	526.5
DR6	577.5	725	443.5	560	1035.3	570	530
DR7	340	410.6	886.7	0	800.7	680.5	800
DR8	627	556.5	1023	1024	759	1025.7	300
DR9	439	738	980	1031.7	1024	900	757

How many possible ways are there for sending one unit from any refinery to any district?

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Payal Gupta

Contributor-Level 10

Number of refineries = 6

Number of depots = 7

Number of districts = 9

Therefore, number of possible ways to send petrol from any refinery to any district is 6 * 7 * 9 = 378.

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New answer posted

8 months ago

Class 12th Chemistry

The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is:

[Given: The threshold frequency of platinum is 1.3 * 10¹⁵s^-¹ and h = 6.6 * 10^-³⁴ J s.]

0 Follower 2 Views

Raj Pandey

Contributor-Level 9

$?_{0} = h υ_{0}$

$= 6.6 * 1 0^{- 34} * 1.3 * 1 0^{15} J$

^{$= 8.58 * 1 0^{- 19} J$}

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8 months ago

Class 12th Chemistry

Which one of the following is correct for the adsorption of a gas at a given temperature on a solid surface?

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Vishal Baghel

Contributor-Level 10

During adsorption of a gas on solid surface, process is exothermic i.e. $Δ H = - v e (Δ H < 0)$ and entropy decreased, because gas particle resides on solid surface. Hence $Δ S < 0 .$

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8 months ago

Class 12th Chemistry

83 g of ethylene glycol dissolved in 625 g of water. The freezing point of the solution is________K. (Nearest integer).

[Use: Molal Freezing point depression constant of water = 1.86 K kg mol^-1

Freezing point of water = 273K

Atomic masses: C : 12.0u, O : 16.0u, H : 1.0u]

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alok kumar singh

Contributor-Level 10

$Δ T_{f} = i * K_{f} * m$

{for ethylene glycol I = 1, due to non-ionisable}

$= 1 * 1.86 * \frac{83 * 1000}{62 * 625} K$

$= 3.984 K \approx 4 K$ (the nearest integer)

Hence, freezing point of solution = 273 K – 4K = 269 K.

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8 months ago

Class 12th Chemistry

The major product formed in the following reaction is:

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Vishal Baghel

Contributor-Level 10

Kindly consider the following figure

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8 months ago

Class 12th English

A college stores data on students, showing their gender and performance, on a computer disc. Due to virus, some of the data is lost and only the following could be recovered.

Study the table carefully and answer the questions given below it.

	Performance			Total
	Average	Good	Excellent	Total
Male			50
Female				96
Total		54

However, an expert committee arrived at the following conclusions

I. One-third of the male students were 'average'.

II. 40% of the students were female.

III. Half the total numbers of students were 'excellent'.

What fraction of total excellent students are female excellent students?

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Payal Gupta

Contributor-Level 10

Total number of excellent students = 120

Number of female excellent students = 70

Required fraction

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8 months ago

Class 12th Chemistry

Given below are two statements:

Statement I: Sphalerite is a sulphide ore of zinc and copper glance is a sulphide ore of copper.

Statement II: It is possible to separate two sulphide ores by adjusting proportion of oil to water or by using 'depressants' in a froth flotation method.

Choose the most appropriate answer from the options given below:

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alok kumar singh

Contributor-Level 10

Sphalerite is the sulphide ore of zinc (ZnS) and copper glance Cu₂S is the sulphide ores of copper. Two sulphide ores can be separated by adjusting proportion of oil to water or by using depressant in froth flotation method.

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New answer posted

8 months ago

Class 12th English

A college stores data on students, showing their gender and performance, on a computer disc. Due to virus, some of the data is lost and only the following could be recovered.

Study the table carefully and answer the questions given below it.

	Performance			Total
	Average	Good	Excellent	Total
Male			50
Female				96
Total		54

However, an expert committee arrived at the following conclusions

I. One-third of the male students were 'average'.

II. 40% of the students were female.

III. Half the total numbers of students were 'excellent'.

The ratio of female 'good' students to male 'average' students is

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Payal Gupta

Contributor-Level 10

Number of female good students = 8

Number of males average students = 48

Required ratio = 8 : 48 = 1 : 6

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New answer posted

8 months ago

Class 12th Chemistry

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Photochemical smog causes cracking of rubber.

Reason (R): Presence of ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate in phtochemical smog makes it oxidizing.

Choose the most appropriate answer from the options given below:

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alok kumar singh

Contributor-Level 10

Photo-chemical smog is the mixture of various component like, O₃, NO, acrolein formaldehyde and peroxyacetyl nitrate and other oxidizing agents, which causes the cracking of rubber.

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