What are the three main classes of elements? Provide two physical properties for each class of elements

Nicotine has two rings and M+=162.1157 by high-resolution Mass Spectroscopy. Give the molecular formula for nicotine and calculate the number of double bonds.

The statement that people who exercise for an hour may have lower cholesterol levels is it a hypothesis, law, or observation?

What is the acceleration of this object? The object's mass is 2 kg. Small box with dot in the middle. Arrows originate at dot. Arrow up and Arrow down are same length.

55. What information does a balanced equation provide?

The plants shown bloom in summer. Which statement explains why the plants bloom in summer? The nights are shorter. The nights are longer. The nights are colder. The nights are warmer.

Air is transferred from a 75 L tank where the pressure is 125 psi and the temperture is 288 k to a tire with a volume of 6.1 L and a pressure of 25 psi. What is the new temperture.

Which of the following is a measure of randomness in a system? A) entropy. B) kinetic energy. C) potential energy. D) chemical energy.

What substance can be broken down by chemical means? A) ammonia B) aluminum C) antimony D) argon (Castle learning question)

How the law of conservation of mass could be useful for investigating chemical changes

A covalent chemical bond is one in which outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms. protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms.