Which of the following most likely happens during a chemical change?

No new substances are formed.

Properties of a substance remain unchanged.

Composition of a substance is same as before.

Different atoms than before are introduced after the change.

what is the total amount of energy required to remove the most loosely bound electron from each atom in a mole of gaseous Ca

When you open a bottle of soda, bubbles of carbon dioxide start appearing. Is this a chemical or physical change and why?

In a heating curve, when is the temperature constant? need answers! 1. during a phase change 2. during a pressure change 3. during a change in kinetic energy 4. during a change in molecular velocity

Given the following chemical reaction: 2 O2 + CH4 CO2 + 2 H2O What mass of CH4 is required to completely react with 100 grams of O2? 6 C 12.01 Carbon 1 H 1.01 Hydrogen 8 O 16.00 Oxygen A. 10 grams CH4 B. 20 grams CH4 C. 25 grams CH4 D. 45 grams CH4

What is the mass number most similar to? The average mass of all isotopes of the element The sum of the atomic numbers of all isotopes The sum of the Masses of all the isotopes The average charge of all ions of the element

An ion has a charge of 2 - and 18 electrons. A) From which atom does this ion form? B) How do you know?

What diseases are spread in warm temperatures?

In 1993 the Minnesota Department of Health set a health risk limit for chloroform in groundwater of 60.0 g/L Suppose an analytical chemist receives a sample of groundwater with a measured volume of 79.0 mL.

A good way for someone to identify similar substances is to measure their densities true or false

At 25 ∘c, kp = 25 for the reaction h2 (g) + i2 (g) ⇌2hi (g). at equilibrium, the partial pressure of both h2 and i2 is 0.296 atm. what is the partial pressure of hi at equilibrium?