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Atoms And Molecules

Question
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Do all elements have a charged valency? Explain.

Solution

All elements do not form ions so their valencies do not have a charge. For example, carbon and silicon have a valency of 4 and nitrogen has a valency of 3. Further molecules containing only non-metals are formed without a charged valency. For example, in carbon tetrachloride (CCl4), carbon has a valency of 4 and chlorine has a valency of 1.

Some More Questions From Atoms And Molecules Chapter

Convert into mole

(a) 12 gm of oxygen gas

(b) 20 gm of water

(c) 22 gm of carbon dioxide.

What is the mass of?

(a) 0.2 mole oxygen atoms.

(b) 0.5 mole of water molecules.

Calculate the number of molecules of sulphur (S8) present in 16 gm of solid sulphur.

Calculate the number of aluminium ions present in 0.56 gm of aluminium oxide.

Explain law of conservation of mass.

50 g of 10% lead nitrate is mixed with 50 g of 10% sodium chloride in a closed vessel. After the reaction has taken place, it was found that 6.83 g of lead chloride was precipitated. Besides, the reaction mixture contained 90 g water and sodium nitrate. Calculate the amount of sodium nitrate formed.

Name and explain two important laws of chemical combination ?

What are the postulates of Dalton’s atomic theory of matter?

Hydrogen and oxygen combine in two different ways to produce water and hydrogen peroxide. Which of Dalton’s law does this observation confirm? Explain.

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