The property of all ionic compounds that makes chalk particularly useful for writing on a chalkboard is : Hardness and Brittleness
Those properties make chalk leaves residues on the board every time friction happen between the chalk and the board
hope this helps<span />
I think the veins absorb the photons because they're located at the top part of a leaf while the stomata that serves as the leaf's lungs are found at the under side.
For centuries scientists thought the Universe always existed in a largely unchanged form, run like clockwork thanks to the laws of physics. But a Belgian priest and scientist called George Lemaitre put forward another idea. In 1927, he proposed that the Universe began as a large, pregnant and primeval atom, exploding and sending out the smaller atoms that we see today.
His idea went largely unnoticed. But in 1929 astronomer Edwin Hubble discovered that the Universe isn’t static but is in fact expanding. If so, some scientists reasoned that if you rewound the Universe's life then at some point it should have existed as a tiny, dense point. Critics dismissed this: the celebrated astronomer Fred Hoyle sarcastically called this concept the “Big Bang Theory"
The answer is C. Golgi Apparatus
