
Those reaction in which two or more substances combine to form a one new substance are called Combination reaction
In this reaction, We can add :
- Two or more elements can combine to form a compound.
- Two or more compounds can combine to from a one new compound.
- An element and a compound can combine to form a new compound.


In this, Hydrogen is an element and Oxygen is another element. Both are combined to form compound 'Hydrogen oxide'. Hydrogen oxide is commonly known as water.
Answer:
Explanation:
We shall apply law of conservation of mechanical energy for projectile being thrown .
Total energy on the surface = total energy at height h required
a ) At height h , velocity = .351 x ( 2 GM/R x h )



h = .14 R
b )


h = .54 R
c ) least initial mechanical energy required at launch if the projectile is to escape Earth
= GMm / R + 1/2 m (2GM/R)
= 0
Reflection- looking at yourself in a mirror and seeing the moon in the sky
Refraction- putting on your glasses in order to see more clearly and the pencil looks like it’s bent when you stick one end of it in water.