Its the second one. Add the exponents and you'll get 7
Water is molecule formed by the covalent bonding of two atoms of hydrogen with one atom of oxygen. The chemical and physical properties of water are different from each of it's constituent elements Oxygen and Hydrogen. The properties of a drop of water will depend on the simplest unit of water, which is the water molecule 
. Therefore, the smallest unit of the water drop that retains all the physical and chemical properties exhibited by a sample of water is the molecule.
Answer:
See explaination
Explanation:
Please kindly check attachment for the step by step solution of the given problem.
H=(2x1.008)=2.016
O= 15.999
15.999
+ 2.016
______
18.015 g/mol :)
The most likely reason is that basalt is an extrusive rock, while granite is an intrusive rock. What this means is that basalt forms at the surface of the earth, where temperatures are cooler. Because of the cooler external temperature, basalt cools relatively quickly, and there isn't as much time for mineral crystals within the rock to align to form larger crystals while the rock is cooling. Granite, on the other hand, forms below the surface of the earth, where temperatures are significantly higher. Therefore, it doesn't cool as quickly, and the minerals within granite have more time to form larger crystals and the rock cools.
