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प्रश्न
Define the following term with an example.
Element
उत्तर
Element: It is a substance that cannot be broken down into simpler substance by chemical means
Ex.: Oxygen, Hydrogen, Gold & Helium.
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संबंधित प्रश्न
TRUE \ FALSE
Elements combine in definite proportions to form compounds.
TRUE \ FALSE
Elements having a tendency to accept electrons are called metals
WRITE SHORT ANSWER
Name three inert gases.
ANSWER IN DETAIL
Enlist the features of Bohr’s model of an atom. How did he correct the Rutherford’s model ?
Write the names of the elements present in the following compound.
Common salt
Write the names of the elements present in the:-
Ammonia
Define: Mass number
What is the maximum number of electrons present in:
1. first shell
2. second shell
3. third shell and
4. fourth shell
Name three non-metals/radicals which have valency -1, -2, and -3.
What does the word ‘atom’ mean?
A certain particle ‘X’ has 17 protons, 18 electrons and 20 neutrons.
What is the atomic numebr of X ?
Fill in the blank
If an atom loses an electron, it acquires ______ a charge.
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.
An atom of element E contains 3 protons, 3 electrons and 4 neutrons :
(a) What is its atomic number?
(b) What is its mass number?
(c) Write the electronic configuration of the element E.
(d) State whether element E is a metal or non-metal. Why?
(e) What type of ion, cation or anion, will be formed by an atom of element E? Why
(f) Write the symbol of the ion formed by an atom of element E.
(g) What could element X be?
Which of the following statement is correct about the atom of an element ?
Give scientific reason.
All the mass of an atom is concentrated in the nucleus.
The electron shell ______ is nearest to the nucleus.
Name the gas that.
Turns moist starch iodide paper blue black.
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
Which element will lose electron?
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
What will be the charge present of the molecule XY after chemical combination?
The electronic structure [configuration] of fluorine can be written as 2, 7. In a similar way give the electronic configuration of phosphorus
A compound containing one atom of carbon and two atoms of oxygen is ______.
Define the following term with an example.
Metalloid
Which of the following statements made by Dalton has not undergone any change?
1 mole of Gold and Silver contain same number of atoms.
The graphite refill used is pencil is made of element called ______.
The ______ are combination of atoms of various elements or the same element.
