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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

Define :- Molecule - Chemistry

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प्रश्न

Define:- Molecule

व्याख्या
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उत्तर

Molecule : Molecule is the smallest unit of a compound (or an element) which always has an independent existance.

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पाठ 4: Atoms, Molecules and Radicals - Exercise

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सेलिना Concise Chemistry [English] Class 7 ICSE
पाठ 4 Atoms, Molecules and Radicals
Exercise | Q 1.2

संबंधित प्रश्‍न

Tick the most appropriate answer.

Who discovered that radioactive rays are given out by uranium?

  1. Henri Becquerel
  2. Marie Curie
  3. Pierre Curie
  4. Schmidt

TRUE \ FALSE

Elements combine in definite proportions to form compounds.


Define:- Radicals


Write the names of `("NH"_4)_2"SO"_4` compounds:


Define: Mass number


What does the word ‘atom’ mean?


State Dalton’s atomic theory.


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?


State two observations which show that atom is not indivisible.


The electronic configuration of an element Z is 2, 8, 8.
(a) What is the atomic number of the element?
(b) State whether element Z is a metal or a non-metal.
(c) What type of ion (if any) will be formed by an atom of element Z? Why?
(d) What is special about the outermost electron shell of the atom of this element?
(e) Give the name and symbol of element Z.
(f) Name the group of elements to which Z belongs.


Define the following term:

Atom


Deduce from the datum provided.

Datum To deduce
\[\ce{_11^23Na}\] Neutron number
\[\ce{_6^14C}\] Mass number
\[\ce{_17^37 Cl}\]  Proton number

The basic unit of matter is ______.


1 mole of Gold and Silver contain same number of atoms.


Dalton’s atomic theory successfully explained

(i) Law of conservation of mass

(ii) Law of constant composition

(iii) Law of radioactivity

(iv) Law of multiple proportions


The graphite refill used is pencil is made of element called ______.


The most abundant type of atom is the universe is ______.


The ______ are combination of atoms of various elements or the same element.


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