## What is gold number ?

It is the amount of lyophilic sol required in milligrams to prevent the the coagulation of 10ml gold sol by the addition of 1 ml, 10% NaCl solution .

## Why is carbon important for forming complicated molecules? Or why carbon makes a large number of molecules ?

The answer to this question is very simple . There are two major reasons behind it. 1. Catenation :- It is the property by which the carbon can make long chains, branched chains and ring or cylic structural by joining with its own atoms. Due to this it can make a variety of molecules. 2.Continue reading “Why is carbon important for forming complicated molecules? Or why carbon makes a large number of molecules ?”

## What is Wurtz reaction?

It is the reaction between alkyl halides and sodium in the dry ether to give alkanes with higher number of carbon. 2R-X + 2 Na —> R-R +2NaX

## What is Coordination number

It is the number of lattice points touching one lattice point in a crystalline solid. For example in case of Sodium chloride it is 6 .

## Some important terms

1. Co-ordination number Number of spheres touching one Sphere in a close packed structure is called co-ordination number of a lattice 2. Unit cell The smallest repeating pattern in a crystal lattice is called a unit cell. Characteristics of unit cell Are unit cell has a characteristic dimensions along the three edges a,b,c and interfacialContinue reading “Some important terms”

## How many atoms are there in 1 gram of carbon?

For  calculation of number of atoms we have to calculate the number of moles present in 1gram carbon. Multiply the number of moles with Avogadro number. Step I  Number of moles in 1 gram of carbon = given mass / molar mass Molar mass (molecular or atomic mass expressed in grams) = 12g So theContinue reading “How many atoms are there in 1 gram of carbon?”

## How many oxygen atoms are there in 90g of H2O molecule?

1 molecule of H2O has 1 atom of oxygen. Firstly we will calculate the number of atoms in 90g of H2O. we will explain it in two steps:- Step I:- No.of moles of H2O = given mass / molar mass No. of moles = 90/18 = 5 moles No. Of molecules = No. of molesContinue reading “How many oxygen atoms are there in 90g of H2O molecule?”

## What is the number of moles of O-atom in 126 AMU of HNO3?

Here we have 126 AMU of HNO3, Molar mass of HNO3 is 1+14+16×3 = 63amu Number of molecules of HNO3 are = 126/63 = 2 Here we have 2 molecules Each molecule have 3 atoms of oxygen. So no. of oxygen atoms= 3×2 =6 atoms No. Of moles = given particles/ avogadro number No. ofContinue reading “What is the number of moles of O-atom in 126 AMU of HNO3?”