Question

why our blood is red

Answer 1

Due to the presence of haemoglobin.

Answer 2

our blood contains haemoglobin. This haemoglobin contains metals like iron in it's nutrient form and it is dissloved in it. In actual the iron present gives the red colour and we can also say that haemoglobin also gives red colour to our blood. this is property is also used in red soil.. as iron is present in the red soil. It appears red. it is a property of iron nutrient.