What is the most obvious sign of a chemical change in this reaction.

a. a gas was produced.

b. the powder mixed with the water.

c. there was a change in temperature. eliminate

d. the powder dissolved in the water.?

Sodium on periodic table

The model below shows an atom of an element. 9 light grey and 8 dark grey balls sit at the center with 2 concentric black rings around them. The inner ring has 2 medium grey balls on it, and the outer ring has 6 medium grey balls on it.

Compare electron energy levels and nuclear rings (both physically and chemically)

What happens to entropy during this dissolving process.

How much heat must be added to heat 0.750 g of water from 20.0°C to 40.0°C? (Remember, Q=C * m * ΔT) The specific heat of water is 4.186 joule/gram. Question 4 options: A) 322 kJ B) 126 kJ C) 62.8 J D) 62.8 kJ

Which of the following is not required for osmosis to occur? View Available Hint (s) Which of the following is not required for osmosis to occur? selectively permeable membrane water concentration gradient cellular energy

The volume of 1 mole of o2 gas at T=273k P=1atm is? A 6.02 x 10^-23 ml B 760 L C 22.4 L D 2.24 L E 224 L

There are two stable isotopes of bromine. Their masses are 78.9183 and 80.9163 amu. If the average atomic mass of bromine is 79.9091 amu, what is the natural abundance of the heavier isotope? percent abundance of 81Br __%

If 1.00 mol of argon is placed in a 0.500-L container at 20.0 ∘C, what is the difference between the ideal pressure (as predicted by the ideal gas law) and the real pressure (as predicted by the van der Waals equation) ? For argon, a=1.

Which of these is a covalent compound? 1. AICI3 2. CO 3. MgO 4. LiCI