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Class 12th Maths

Let $A = (\begin{matrix} 1 & - 1 & 0 \\ 0 & 1 & - 1 \\ 0 & 0 & 1 \end{matrix}) a n d B = 7 A^{20} - 20 A^{7} + 2 I,$ where I is an identity matrix of order 3 × 3. If B = $[b_{i j}],$ then b₁₃ is equal to……………

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Class 12th Chemistry

The potassium ferrocyanide solution gives a Prussian blue colour, when added to:

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Class 12th Atomic Masses and Composition of Nucleus

How does number of neutrons affect the stability of nucleus?

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Class 12th Maths

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Class 12th Chemistry

The potassium ferrocyanide solution gives a Prussian blue colour, when added to:

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Class 12th Chemistry

Given below are two statements:

Statement I : The nucleophilic addition of sodium hydrogen sulphite to an aldehyde or a ketone involves proton transfer to form a stable ion.

Statement II : The nucleophillic addition of hydrogen cyanide to an aldehyde or a ketone yields amine as final product.

In the light of the above statements, choose the most appropriate answer from the options given below:

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alok kumar singh

Contributor-Level 10

Nucleophilic addition of sodium hydrogen sulphite to aldehyde or ketone is a;

$N a H S O_{3} ? N a^{+} + H S O_{3}^{?}$

So; nucleopilic addition of sodium hydrogen sulphite to an aldehyde or a ketone involves proton transfer to form a stable ion.

Addition of hydrogen cyanide;

Final product is cyanohydrin.

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Class 12th English

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

The regular mathematics faculty could not teach because of being sick. As a stop gap arrangement different visiting faculty taught different topics on 4 different days in a week. The scheduled time for class was 7:00 am with maximum permissible delay of 20 minutes. The monsoon made the city bus schedules erratic and therefore the classes started on different times on different days.

Mr. Singh didn't teach on Thursday. Calculus was taught in the class that started at 7:20 am. Mr. Chatterjee took the class on Wednesday, but he didn't teach probability. The class on Monday

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alok kumar singh

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Professor	Day	Timing	Subject
Mr. Singh	Friday	07:10	Set theory
Mr. Chatterjee	Wednesday	07:20	Calculus
Mr. Dutta	Monday	07:00	Probability
Mr. Banerjee	Thursday	07:05	Ratio and Proportion

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Class 12th Nuclei

Why do some elements have fractional atomic masses?

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Jaya Sharma

Contributor-Level 10

Most elements exist as a mixture of isotopes in nature. Isotopes are atoms of same elements that have same number of protons but they have different numbers of neutrons. Since the number of neutrons may vary, different isotopes of same element have different atomic masses.

The atomic mass of an element is a weighted average of atomic masses of its isotopes considering their natural abundances. The weighted average is calculated by multiplying atomic mass of every isotope by its natural abundance and then adding these products.

The atomic mass is an average that accounts for different masses and abundances of isotopes that results in a fr

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Class 12th English

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

There are five friends P, Q, R, S and T. Two of them play table tennis while the other three play different games, viz. football, cricket and chess. One table tennis player and the chess player stay on the same floor while the other three stay on floors 2, 4 and 5. Two of the players are industrialists while the other three belong to different occupations viz. teaching, medicine and engineering. The chess player is the oldest while one of the table tennis players, who plays at the national level is the youngest. The other table tennis player who plays at the regional lev

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