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प्रश्न
Define the following term with an example.
Compound
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उत्तर
Compound: A compound is a pure substance that is formed when the atoms of two or more elements combine chemically in definite proportions.
Ex: H20, NaCl.
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संबंधित प्रश्न
Why is it not possible to see an atom with naked eyes?
The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes `""_8^16X" and """_8^18X` in the sample?
MATCH THE COLUMNAS
| 1. Jpham Dalton | a. Neutrons |
| 2. Atom | b. Model of the atom |
| 3. Chadwick | c.The atomic theory of matter |
| 4. Rutherfrod | d. Positively charged |
| 5. Protons | e. Electricity neutral |
| 6. Nuclear fusion | f. Generator of electricity |
| 7.Gamma -rays | g. High penetrating power |
| h.Energy in sun |
TRUE \ FALSE
Elements combine in definite proportions to form compounds.
Define:- Molecule
Write the names of the elements present in the :-
Sulphuric acid
What is the maximum number of electrons present in:
1. first shell
2. second shell
3. third shell and
4. fourth shell
Fill in the blank
An excess of electrons produces a ________ charge.
What is the usual symbol for (a) and electron (b) a proton, and (c) a neutron?
Name the unit in which the radius of an atom is usually expressed.
Fill in the following blanks with suitable words :
In water, the proportion of oxygen and hydrogen is .............. by mass.
What is an atom ? How do atoms usually exist ?
Find the mass of 2 moles of nitrogen atoms.
Give scientific reason.
All the mass of an atom is concentrated in the nucleus.
Draw the electron dot structure of this compound.
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
Which will form negative ion?
State the meaning of the term – (a) atom, (b) molecule, (c) radical – with a suitable example.
Define – Atom.
Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order
- Rutherford’s atomic model
- Thomson’s atomic model
- Bohr’s atomic model
Write any two observations which support the fact that atoms are divisible.
