Answer: physical
Explanation: freezing and melting are physical changes.
As the concrete has cement, gravel, crushed rocks, sand, and water of different physical state and can be separated by physical methods hence it should be called as a mixture.
As the components have significant physical boundaries which clearly identify their presence, the mixture is heterogeneous and not homogeneous.
Thus this is a concrete is a heterogeneous mixture of cement, gravel, crushed rocks, sand, and water
It required a fixed finite amount these zones are known as energy levels
Answer:
E) NaF and SrO
Explanation:
The ionic bonding occurs between atoms with a great difference in electronegativity. This usually happens between a metal and a non-metal.
<em>In which pair do both compounds exhibit predominantly ionic bonding? </em>
A) KCl and CO₂. NO. C and O are non-metals and present covalent bonding.
B) SO₂ and BaF₂. NO. S and O are non-metals and present covalent bonding.
C) F₂ and N₂O. NO. Both compounds contain non-metals and present covalent bonding.
D) N₂O₃ and Rb₂O. NO. N and O are non-metals and present covalent bonding.
E) NaF and SrO. YES. Na and Sr are metals while F and O are non-metals.
Adenine , guanine, cytosine and thymine
