The picture shows the bonds between atoms in two allotropes of carbon. Which allotrope is harder? Explain your answer.

The two allotropes of carbon are: Allotrope 1 - Graphite In the given structure of Graphite all the carbon atoms in are said to have stable chemical bonds with that of the other three carbon atoms, thus making the sheets. The carbon atoms in the Graphite structure are sp 2 hybridised and are directed in the same plane thus forming hexagonal rings. Due to this reason graphite is soft. Allotrope 2 - Diamond All the carbon atoms of Diamond make strong chemical bonds with that of the four other carbon atoms, thus making a perfect tetrahedron structure and on throughout the crystal. The carbon atoms, here are sp 3 hybridised, and the bond lengths of carbon-carbon atom are equal. Hence, Diamond forms a three-dimensional network of strong covalent bonds. Thus, it is the hardest substance. Hence, it can be concluded that Allotrope is harder than Allotrope 1.

pH is measured on a scale of 0 to 14 , with lower values indicating high hydrogen ion concentration (more acidic) and higher values indicating low hydrogen ion concentration (less acidic). A pH of 7 is considered as neutral. Every whole unit in pH represents a ten-fold increase in or decrease in hydrogen ion concentration. What would the hydrogen ion concentration of a solution of pH 4 be compared to a solution of pH 8 ?

Every whole unit in pH represents a ten-fold increase in or decrease in hydrogen ion concentration. H + is the antilog of negative pH . H + = 10 - pH Hydrogen ion concentration of a solution of pH 4 is: H + = 10 - 4 mol / L Hydrogen ion concentration of a solution of pH 8 is: H + = 10 - 8 mol / L H + = 10 - 4 10 - 8 = 10 4 Therefore, Hydrogen ion concentration of a solution of pH = 4 is 10 4 times as compared to that of pH = 8 .

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You are given three identical $10 Ω$ resistors and a $12 V$ cell. Draw the circuit diagram to show how the resistors can be connected with the $12 V$ cell so that the total heat produced in the circuit is the MINIMUM.

Important Questions on Carbon and its Compounds

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Carbon and its Compounds>Exercise>Q 30

5 mL

of dilute acetic acid were added to

5 mL

of water and the mixture was shaken for one minute. It was observed that

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Carbon and its Compounds>Exercise>Q 31

A saturated hydrocarbon has fifty hydrogen atoms in its molecule. The number of carbon atoms in its molecule will be:

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Carbon and its Compounds>Exercise>Q 32

Soaps are prepared by the alkaline hydrolysis of

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Carbon and its Compounds>Exercise>Q 34

C_{6} H_{14}

, the number of possible isomers is:

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Carbon and its Compounds>Exercise>Q 9

The picture shows the bonds between atoms in two allotropes of carbon.

Question Image

Which allotrope is harder? Explain your answer.

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Acids, Bases and Salts>Exercise>Q 24

pH

is measured on a scale of

0

14

, with lower values indicating high hydrogen ion concentration (more acidic) and higher values indicating low hydrogen ion concentration (less acidic). A

pH

7

is considered as neutral. Every whole unit in

pH

represents a ten-fold increase in or decrease in hydrogen ion concentration. What would the hydrogen ion concentration of a solution of

pH 4

be compared to a solution of

pH 8

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Acids, Bases and Salts>Exercise>Q 26

Dipti has three flasks containing dilute hydrochloric acid, dilute sulphuric acid and dilute sodium hydroxide respectively. The flasks are not labelled, and she does not have any pH indicator.
(a) Which of the solutions will she be able to identify just by making mixtures of pairs of the substances.
(b) What observation will help her to make this identification?

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Science Textbook of Competency Based Questions for Class X>Chapter 4 - Acids, Bases and Salts>Exercise>Q 23

Aditi finds that a mixture of an acid and a base does not change the colour of either red or blue litmus paper. Compare the amounts of

H^{+}

and

{OH}^{-}

in the solution.

You are given three identical 10 Ω resistors and a 12 V cell. Draw the circuit diagram to show how the resistors can be connected with the 12 V cell so that the total heat produced in the circuit is the MINIMUM.

Important Questions on Carbon and its Compounds

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You are given three identical $10 Ω$ resistors and a $12 V$ cell. Draw the circuit diagram to show how the resistors can be connected with the $12 V$ cell so that the total heat produced in the circuit is the MINIMUM.