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What do you understand by significant figures? Please answer this question urgently. Please. Please. Please.

What do you understand by significant figures?
 
Please answer this question urgently. Please. Please. Please.

Grade:10

25 Answers

Gaurav Yadav
406 Points
3 years ago

Hey student.

 

Significant figures are meaningful digits that are known with certainty. The uncertainty in experimental or the calculated value is indicated by mentioning the number of significant figures.

 

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Nandini Sharma
25 Points
3 years ago
State law of definite proportions.
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
The Law of definite proportions states that a given compound always contains exactly the same proportion of elements by weight.
 
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Nandini Sharma
25 Points
3 years ago
State Avogadro’s law.
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
According to Avogadro’s law, equal volumes of gases at the same temperature and pressure should contain equal number of molecules.
 
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Nandini Sharma
25 Points
3 years ago
What is formula mass?
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
When a substance does not contain discrete molecules as their constituent units and have a three dimensional structure, formula mass is used to calculate molecular mass which is sum of all the atomic masses of atom present in the formula.
 
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Nandini Sharma
25 Points
3 years ago
What is stoichiometry?
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
Stoichiometry deals with the calculations of masses of reactants and products involved in chemical reactions.
 
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Nandini Sharma
25 Points
3 years ago
The substance which gets used up in any reaction is called --------------
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
The substance that gets used up in any reaction is called limiting reagent.
 
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Nandini Sharma
25 Points
3 years ago
How can we say that sugar is solid and water is liquid?
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
Sugar has close packing of constituent particles, have its own volume and shape therefore, it can be said to be solid whereas in water the constituent particles are not as closely packed as in solid. It has definite volume but not definite shape. Therefore it is a liquid.
 
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Nandini Sharma
25 Points
3 years ago
What is the difference between mass & weight? How is mass measured in laboratory?
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 
Mass of a substance is the amount of matter present in it while weight is the force exerted by gravity on an object the mass of a substance is determined with the help of an analytical balance in the laboratory.
 
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Nandini Sharma
25 Points
3 years ago
Write Postulates of Dalton’s atomic theory.
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 

Postulates of Dalton’s atomic theory –

1. Matter consists of indivisible atoms.

2. All the atoms of a given element have identical properties including atomic mass. Atoms of different element differ in mass.

3. Compounds are formed when atoms of different elements combine in a fixed ratio.

4. Chemical reaction involves reorganization of atoms. These are neither created nor destroyed

 

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Nandini Sharma
25 Points
3 years ago

Give one example each of a molecule in which empirical formula

and molecular formula are (i) same (ii) Different.

 

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Gaurav Yadav
406 Points
3 years ago
Hey student.
 

(i) Same molecular formula and empirical formula. Carbon dioxide, both is CO2.

(ii) When molecular formula and empirical formula are different –

Hydrogen peroxide: molecular formula is H2O2 and empirical formula is HO

 

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Nandini Sharma
25 Points
3 years ago
Which experiment led to the discovery of electrons and how?
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 

The cathode ray discharge tube experiment performed by J.J. Thomson led to the discovery of negatively charged particles called electron.

A cathode ray tube consists of two thin pieces of metals called electrodes sealed inside a glass tube with sealed ends. The glass tube is attached to a vacuum pump and the pressure inside the tube is reduced to 0.01mm. When fairly high voltage (10, 000V) is applied across the electrodes, invisible rays are emitted from the cathode called cathode rays. Analysis of this rays led to the discovery electrons.

 

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Nandini Sharma
25 Points
3 years ago
Give the main properties of canal ray experiment.
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 

The canal ray experiment led to the discovery of –

(i)The anode rays, travel in straight line

(ii)They are positively charged as they get deflected towards the –ve end when subjected to an electric and magnetic field.

(iii)They depend upon the nature of gas present in the cathode tube.

(iv)The charge to mass ration (e/m) of the particle is found to depend on the gas from which they originate.

(v)They are also material particles

The analysis of these proportions led to the discovery of positively charged proton.

 

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Nandini Sharma
25 Points
3 years ago
Give the main features of Thomson’s Model for an atom.
 
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Gaurav Yadav
406 Points
3 years ago
Hey student.
 

J.J. Thomson proposed that an atom consists of a spherical sphere (radius of about 10-10m)in which the positive charges are uniformly distributed the electrons are embedded into it in such a manner so as to give stable electrostatic arrangement.

This model is also called raisin pudding model.

 

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