Four statements about atoms are listed.
1 The centre of an atom is positively charged.
2 Protons and electrons are located in the nucleus.
3 Protons and electrons have the same mass.
4 Most of the mass of an atom is in the nucleus.
Which statements are correct?
1 and 2
1 and 4
2 and 3
3 and 4
The structure of an atom of element X is shown.
key
- = electron
n= neutron
p= proton
What is element X ?
boron
carbon
sodium
sulfur
4 X and Y are two different elements.
X and Y have the same number of nucleons.
Which statement about X and Y is correct?
They have the same physical properties.
Their atoms have the same number of electrons.
They are in different groups of the Periodic Table.
They have different relative masses.