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प्रश्न
A change in the physical state can be brought about
विकल्प
only when energy is given to the system
only when energy is taken out from the system
when energy is either given to or taken out from the system
without any energy change
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उत्तर
when energy is either given to or taken out from the system
When energy is given to the system the solid state changes to liquid. When energy is taken out from a liquid it changes to solid e.g., ice changes to water and water to water vapours when heat energy is given. Water vapours or steam condense to water and water freezes to ice when energy is decreased.
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संबंधित प्रश्न
Write the names of the elements present in the :-
Sulphuric acid
Write the names of `"Na"_3"PO"_4` compounds :
Fill in the blank:
Atoms are _____
Fill in the blank
An ion with negative charge is called _______
Define: Relative atomic mass
Name two particles found inside the nucleus. What are they collectively called ?
Give two examples for each of ionic and covalent bond.
Who originated the word ‘atom’ ?
Fill in the blank
If an atom loses an electron, it acquires ______ a charge.
Fill in the blank
An excess of electrons produces a ________ charge.
Fill in the blank
A deficiency of electrons produces a ________ charge.
State two observations which show that atom is not indivisible.
For the symbols H, D and T, write the subatomic particles (protons, neutrons and electrons) found in each one of them.
Give scientific reason.
All the mass of an atom is concentrated in the nucleus.
The electron shell ______ is nearest to the nucleus.
In all atoms of an element
An element is composed of ______ atoms.
Define the term ions or radicals.
In the nucleus of `""_20"Ca"^40`, there are ______
______ is a substance that is made up of three oxygen atoms chemically combined.
