Recent questions tagged medium

The elements $_{30}Zn,_{48}Cd$ and $_{80}Hg$ belong to

asked Jul 25, 2014 by sreemathi.v

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The atomic number of In is 49.It belongs to

asked Jul 25, 2014 by sreemathi.v

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An element X belongs to Group 16 and $5^{th}$ period.Its atomic number is

asked Jul 25, 2014 by sreemathi.v

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Which of the following statements regarding Boron is not correct ?

asked Jul 25, 2014 by thanvigandhi_1

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The atomic numbers of elements of the lanthanide series lie in the range of

asked Jul 25, 2014 by sreemathi.v

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The total number of elements in Groups 8 to 10 of the periodic table is

asked Jul 25, 2014 by sreemathi.v

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The atomic numbers of elements of the second inner transition elements lie in the range of

asked Jul 25, 2014 by sreemathi.v

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Which of the following facts regarding boron and silicon is not true ?

asked Jul 25, 2014 by thanvigandhi_1

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An element X belongs to Group 14 and $2^{nd}$ period of the periodic table.Its atomic number will be

asked Jul 25, 2014 by sreemathi.v

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The number of elements in the fourth period of the periodic table is

asked Jul 25, 2014 by sreemathi.v

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The atomic number of element next to $_{53}I$ in the same group is

asked Jul 25, 2014 by sreemathi.v

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Which of the following equations is not correctly formulated ?

asked Jul 25, 2014 by thanvigandhi_1

1 answer

The elements with atomic numbers 21 to 30 belong to

asked Jul 25, 2014 by sreemathi.v

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The oxidation state of Sc in $Sc_2Si_2O_7$ is

asked Jul 25, 2014 by sreemathi.v

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The charge $x$ of $Si_6O_{18}^x$ will be

asked Jul 25, 2014 by sreemathi.v

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Which one of the following is a covalent carbide?

asked Jul 25, 2014 by sreemathi.v

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Which of the following elements is not the constituent of zeolite A

asked Jul 25, 2014 by sreemathi.v

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Which of the following statements is correct?

asked Jul 25, 2014 by sreemathi.v

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Which of the following bonds has the highest bond energy ?

asked Jul 25, 2014 by sreemathi.v

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A certain reaction is first order, and 540 s after initiation of the reaction, 32.5% of the reactant remains. At what time after initiation of the reaction of the reaction will 10% of the reactant remain?

asked Jul 25, 2014 by balaji.thirumalai

1 answer

Which of the following is an allylide?

asked Jul 25, 2014 by sreemathi.v

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Which of the following is a acetylide?

asked Jul 25, 2014 by sreemathi.v

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Which of the following is a methanide?

asked Jul 25, 2014 by sreemathi.v

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What is the rate of a reaction if $[A]_o = 560\;M$, $[B]_o = 0.2\;M$, and 2nd order rate constant is $0.1\;M^{-1}s^{-1}$?

asked Jul 25, 2014 by balaji.thirumalai

1 answer

What is the concentration of $A$ at time $45\;s$ if $[A]_o = 1\;M$, $[B]_o = 45\;M$, and 2nd order rate constant is $0.6\;M^{-1}s^{-1}$?

asked Jul 25, 2014 by balaji.thirumalai

1 answer

A ball is dropped from the roof of a building . An observer notes that the ball takes $0.1$ s to cross over a window 1 m in height . After crossing the window , the ball takes another 1.00 s to come to the bottom of the building . What is height of the building and how high is the window. Take $g=10 ms^{-2}$

asked Jul 25, 2014 by meena.p

1 answer

Which of the following fuel gases has the highest calorific value?

asked Jul 25, 2014 by sreemathi.v

1 answer

Hydrolysis of $SiF_4$ in alkaline medium produces

asked Jul 25, 2014 by sreemathi.v

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Drops are falling at regular intervals of time from the roof of a building 16 m high. If the first drop reaches the ground at the instant the fifth drop start falling, find the heights of the various drops at the instant the first drop reaches the ground ?

asked Jul 25, 2014 by meena.p

1 answer

The only stable tetrahalide of lead is

asked Jul 25, 2014 by sreemathi.v

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A juggler is maintaining four balls in motion, making each in turn to rise to height of 20 m.Where will other three balls be at the instant, When one is just leaving his hand? $g= 10ms^{-2}$

asked Jul 25, 2014 by meena.p

1 answer

Which of the following statements is not correct?

asked Jul 25, 2014 by sreemathi.v

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Which of the following statements is not correct?

asked Jul 25, 2014 by sreemathi.v

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Which of the following equations is not actually observed?

asked Jul 25, 2014 by sreemathi.v

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In the purification of lead electrolytically,which of the following facts is not correct?

asked Jul 25, 2014 by sreemathi.v

1 answer

Which of the following is not correct?

asked Jul 25, 2014 by sreemathi.v

1 answer

Which of the following statements regarding glass is not true?

asked Jul 25, 2014 by sreemathi.v

1 answer

The thermal decomposition of phosphine to phosphorus and hydrogen gas is a first order reaction, with a half-life of 35 s at 680$^\circ$C. Calculate the time required for 95% of phosphine to decompose.

asked Jul 24, 2014 by balaji.thirumalai

1 answer

The following data was collected in three different experiments:

asked Jul 24, 2014 by balaji.thirumalai

1 answer

Calculate the value of k for this reaction based on the following data collected in three different experiments:

asked Jul 24, 2014 by balaji.thirumalai

1 answer

A certain first order reaction proceeds through t first order kinetics. The half-life of the reaction is 180 s. What percent of the initial concentration remains after 900s?

asked Jul 24, 2014 by balaji.thirumalai

1 answer

The reaction $A \rightarrow \text{Products}$ is second order in $A$. Initially $[A]_0 = 1.00 M$ and after $25 \; \text{mins}, \;[A] = 0.25\; M$. What is the rate constant for this reaction?

asked Jul 24, 2014 by balaji.thirumalai

1 answer

From the integrated rate law for a first order reaction, $ [A] = [A]_0\; e^{-kt}$. Suppose rate constant, $k = 2.95 X 10^{-3} s^{-1}$, What percent of $A$ remains after $150 \;s$?

asked Jul 24, 2014 by balaji.thirumalai

1 answer

An elementary reaction, $2 A + C \rightarrow D$ , is second order in $A$ and first order in $C$. The rate of this reaction is $2.5 \times 10 ^{-1}1\; M/s$ when the concentrations of $A$ and $C$ are all $3.00\; mM$. What is the rate constant for the reaction?

asked Jul 24, 2014 by balaji.thirumalai

1 answer

Which of the following statements is not correct?

asked Jul 24, 2014 by sreemathi.v

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The dissolution of stannous hydroxide in excess base produces

asked Jul 24, 2014 by sreemathi.v

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Which of the following statements is not correct?

asked Jul 24, 2014 by sreemathi.v

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Which of the following facts is not correct ?

asked Jul 24, 2014 by thanvigandhi_1

1 answer

Calculate the electronegativity of Flourine, given the following: $E_{H-H} = 104.2 \; kcal\;mol^{-1},\; E_{F-F} = 36.6\; kcal\;mol^{-1},\;E_{H-F} = 134.6 \; kcal\;mol^{-1},\;\chi_H = 2.1$

asked Jul 24, 2014 by balaji.thirumalai

1 answer

Which of the following sets of bonds are correctly ordered from least to most polar?

asked Jul 24, 2014 by balaji.thirumalai

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