How many orbitals are found in s subshell?

• 1 orbital

• 2 orbitals

• 5 orbitals

• 3 orbitals

Which of the following molecules has 1s and 3p orbitals overlapping?

• HCl

• CH₄

• N₂

• Cl₂

When a sample whose mass is 1g of phosphorus-35 isotope is left for 14 days, it is found that the mass of the sample decreased by half, this observation does not match ………

• Democritus’s idea of the atom only

• Boyle’s idea of matter only

• Dalton’s atomic model

• Democritus’s and Boyle’s ideas and Dalton’s atomic model.

What does happen to the electron by increasing the distance between its orbital and the nucleus? ……………

• Both its kinetic and potential energies decrease.

• Its kinetic energy decreases and its potential energy increases

• Both its kinetic and potential energies increase

• Its kinetic energy increases and its potential energy decreases

What is the correct order of the orbitals in titanium atom according to the increase of energy? ……………

• 3s < 3p < 3d < 4s

• 3s < 3p < 4s < 3d

• 3s < 4s < 3p < 3d

• 4s < 3s < 3p < 3d

Among the modification of the modern atomic theory in the older theories is ……………

• it is impossible to determine both the position and speed of the 11^th electron in ₁₁Na atom precisely.

• the electron is negatively charged.the electron is negatively charged.

• most of the atomic volume is an empty space

• the spaces between energy levels are forbidden for the electrons

Which of the following statements represents properly the element which is located in period 3, group (VIIA) in the modern periodic table …….?

• Forms an ion whose charge is +1

• One of d-block elements

• Its valence shell contains 5 electrons

• A representative element which is located below fluorine ₉F

which of the following elements differs in the electronic configuration of its valence shell from the other elements in its group? …………..

• ₃₆Kr

• ₂₂K

• ₄Be

• ₂He

The elements which follow neon gas are located in the ……… period.

• First

• Second

• Third

• fourth

How many unpaired electrons are there in the ground state electronic configuration of an atom of aluminum?

• 4 unpaired electrons

• 1 unpaired electron

• 3 unpaired electrons

• 2 unpaired electrons