Science Class 7th

241. Electrons revolve around the nucleus in particular paths called

A) Orbits

B) Shells

C) Revolver

D) Both A & B

 

242. The orbit near the nucleus is called

A) M-shell

B) K-Shell

C) L-Shell

D) None of these

243. Electrons are distributed in the shells according to the general formula

A) 2n^2

B) 2x^2

C) 2x^3

D) None of these

 

244. According to formula electrons in the first shell will be

A) 1

B) 2

C) 3

D) 4

245. The number of protons or electrons present in the atom is called

A) Mass number

B) Molecule number

C) Atomic number

D) None of these

246. Atom has charge_____

A) Positive

B) Negative

C) Neutral

D) None of these

247. The number of electrons and protons in atom are

A) Protons > electrons

B) Electrons > protons

C) Equal

D) None of these

248. Atomic number is denoted by

A) M

B) N

C) Z

D) O

249. Atomic number of Hydrogen is

A) 1

B) 2

C) 4

D) 3

250. Atomic number of helium is

A) 1

B) 2

C) 3

D) 4

251. The sum of the number of protons and numbers of neutrons are called

A) Atomic number

B) Mole

C) Mass number

D) None of these

252. Mass number is denoted by

A) Z

B) Y

C) A

D) X

 

253. Protons and neutrons reside in the nucleus, thus they are also known as

A) Nucleus

B) Nucleons

C) Mass number

D) Atomic number

 

 

254.   The combining capacity of the atoms to form molecules either with same or different elements is known as                      

A)   Velocity

B)   Valency

C)   Molecule

D)   None of these

255. Atoms containing less than electrons in its outermost shell, its valence is equal to the num- ber of electrons present in the valence shell.

A) Four

B) Three

C) Five

D) Two

256. Sodium has one electron in its outermost shell, the Valency of sodium is

A) Two

B) Eight

C) one

D) four

257. _________is a charged particle.

A) Molecule

B) Atoms

C) Bonds

D) Ion

258. Ions are of types.

A) Two

B) Three

C) Four

D) Five

259. If an electron or more than one electrons are removed from an atom, it becomes a positive ion which is also known as

A) Molecule

B) Cation

C) Atoms

D) None of these

260. If an electron or more than one electrons are added to an atom, it becomes a negative ion which is also known as

A) Cation

B) Mass number

C) Anion

D) None of these