which of the following examples agrees with Dalton’s postulates?

• The atoms which are found in a sample of chlorine resemble those which are found in a sample of sulphur

• Atoms which form magnesium are tiny

• Hydrogen can combine with oxygen to form water in more than one numerical ratio.

• The properties of the molecules of hydrogen and oxygen differ from their properties in water molecules.

The electronic configuration of ruthenium ion ₄₄Ru³⁺ is .......

• [Kr], 4d³, 5s²

• [Kr], 4d⁶, 5s²

• [Kr], 4d⁶

• [Kr], 4d⁵

If the element (X) in the periodic table forms the compounds XCl₃, X₂O₃, then (X) is located in group …………

• IIIA

• IIA

• VIIA

• IVA

Principles related to the electronic configuration of the first twenty elements can be used to understand patterns of heavier elements.

In what group would you expect to find an element with the electronic configuration [Xe]4f¹⁴5d¹⁰6s²6p²?

• 15

• 18

• 14

• 19

The group symbol of representative elements is ........

and the group symbol of main transition element is .....

• B,A

• A,B

• d,A

• d,S

The actual electronic configuration of chromium

• (₁₈Ar),4s¹,3d⁶

• (₁₈Ar),4s¹,3d⁵

• (₁₈Ar),4s²,3d5

• (₁₈Ar),4s²,3d⁴

All of the following are among the properties of the elements ₄Be, ₁₂Mg, and ₂₀Ca except that? …….

• The last sublevel s contains 2 electrons

• They are representative elements

• The sublevel p in the valence shell contains a pair of electrons

• They are located in group (2A)

What is the electronic configuration of a calcium ion (Ca)²⁺?

• 1s²2s²2p⁶3s²3p⁴

• 1s²2s²2p⁶3s²3p⁶4s²3d²

• 1s²2s²2p⁶3s²3p⁴4s²

• 1s²2s²2p⁶3s²3p⁶

it determines the number of sublevels in each principal energy level

• spin quantum number

• principal quantum number

• magnetic quantum number

• subsidiary quantum number

it is impossible for two electrons in the same atom to have the same four quantum numbers

• hund rule

• aufbau principle

• pauli exclusion principle

• bohr theory