If it's without milk or sugar - it's a pure substance.
Tea is not a pure substance as it is a mixture of milk and the tea solution, the tea solution containing water, tea leaf particles and sugar particles. Without milk, the tea is still not a pure substance.
Magnesium is an element, so it's a pure substance.
The basic fluid in milk is water but added to the water are proteins, sugars and fats. This makes milk a mixture of substances not a pure substance.
A pure substance is the same throughout. When a substance is 100% something it is pure.
No
It's a pure substance.
Mixture
If it's without milk or sugar - it's a pure substance.
Milk is a complex mixture.
Tea is not a pure substance as it is a mixture of milk and the tea solution, the tea solution containing water, tea leaf particles and sugar particles. Without milk, the tea is still not a pure substance.
Magnesium is an element, so it's a pure substance.
Cream
Tea is a mixture.
Yogurt is not a pure substance because its a mixture of different elements/molecules (Cow milk and sugar and more...) from the Periodic Table
It depends on your definition of pure substance. In its natural state, honey is a pure substance. Natural honey is a pure natural substance producted by bees. However, honey is a mixture of a great many different elements.
The basic fluid in milk is water but added to the water are proteins, sugars and fats. This makes milk a mixture of substances not a pure substance.