The table shows the concentration of some ions present in seawater. name of ion formula of ion concentration of ion in g / dm 3 bromide Br - 0 . 07 calcium Ca 2 + 0 . 04 chloride Cl - 19 . 1 magnesium Mg 2 + 1 . 2 potassium K + 0 . 3 sodium Na + 10 . 6 SO 4 2 - 0 . 8 Which two ions in the table are formed from Group I elements?

Seawater consists of salts of various elements. On electrolysis of seawater, these are separated in the form of ions of sodium, chlorine, potassium, etc. Of all given ions, the two ions formed from Group I elements are sodium and potassium. The elements of this group are known as alkali metals, and they form positive ions. The elements of this group include sodium, lithium, potassium, rubidium, etc.

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Upper Secondary: IGCSE

IMPORTANT

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Rubidium also reacts with water. How does the speed of reaction of rubidium with water compare with that of potassium with water?

Important Questions on Cambridge IGCSE Exam Questions from Paper 2

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Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 6

Sodium has only one stable isotope whereas potassium has several isotopes. What do you understand by the term isotopes?

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Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 6

Sodium has only one stable isotope whereas potassium has several isotopes. How many protons does sodium have in its nucleus? Use the Periodic Table to help you.

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Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 6

How many electrons are there in an atom of potassium?

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Upper Secondary: IGCSE

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Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 6

Uranium has many isotopes. One of these is uranium-

235

(^{235} U)

. What is the main use of this isotope of uranium?

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Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 7

The table shows the concentration of some ions present in seawater.

name of ion	formula of ion	concentration of ion in $g / {dm}^{3}$
bromide	${Br}^{-}$	$0.07$
calcium	${Ca}^{2 +}$	$0.04$
chloride	${Cl}^{-}$	$19.1$
magnesium	${Mg}^{2 +}$	$1.2$
potassium	$K^{+}$	$0.3$
sodium	${Na}^{+}$	$10.6$
	${SO}_{4}^{2 -}$	$0.8$

Which negative ion has the highest concentration in seawater?

EASY

Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 7

The table shows the concentration of some ions present in seawater.

name of ion	formula of ion	concentration of ion in $g / {dm}^{3}$
bromide	${Br}^{-}$	$0.07$
calcium	${Ca}^{2 +}$	$0.04$
chloride	${Cl}^{-}$	$19.1$
magnesium	${Mg}^{2 +}$	$1.2$
potassium	$K^{+}$	$0.3$
sodium	${Na}^{+}$	$10.6$
	${SO}_{4}^{2 -}$	$0.8$

Name the ion with the formula ${SO}_{4}^{2 -}$ .

EASY

Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 7

The table shows the concentration of some ions present in seawater.

name of ion	formula of ion	concentration of ion in $g / {dm}^{3}$
bromide	${Br}^{-}$	$0.07$
calcium	${Ca}^{2 +}$	$0.04$
chloride	${Cl}^{-}$	$19.1$
magnesium	${Mg}^{2 +}$	$1.2$
potassium	$K^{+}$	$0.3$
sodium	${Na}^{+}$	$10.6$
	${SO}_{4}^{2 -}$	$0.8$

Which two ions in the table are formed from Group $I$ elements?

EASY

Upper Secondary: IGCSE

IMPORTANT

Complete Chemistry for Cambridge IGCSE® Second Edition>Chapter 20 - Cambridge IGCSE Exam Questions from Paper 2>CAMBRIDGE IGCSE EXAM QUESTIONS from Paper 2>Q 7

The table shows the concentration of some ions present in seawater.

name of ion	formula of ion	concentration of ion in $g / {dm}^{3}$
bromide	${Br}^{-}$	$0.07$
calcium	${Ca}^{2 +}$	$0.04$
chloride	${Cl}^{-}$	$19.1$
magnesium	${Mg}^{2 +}$	$1.2$
potassium	$K^{+}$	$0.3$
sodium	${Na}^{+}$	$10.6$
	${SO}_{4}^{2 -}$	$0.8$

When seawater is evaporated a number of different compounds are formed. State the name of the compound present in the greatest quantity.

Rubidium also reacts with water. How does the speed of reaction of rubidium with water compare with that of potassium with water?

Important Questions on Cambridge IGCSE Exam Questions from Paper 2

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