Assessment

which of these elements higher in energy and why ?
Mg ₁₂²⁴ Fe ⁵⁵₂₆

The number of protons plus neutrons ?

• mass weight

• Mass number

• atomic number

• atomic weight

The atomic number of an element having 6 protons in its nucleus is

• 13
• 6
• 3
• 12

The nucleus contains

• Atom
• Charges
• Atomic number
• Neutrons +proton
• Electron

A substance that can be observed without changing in matter

• molecule

• chemical property

• physical property

Why can`t extinguished petroleum fires with water? Explain