A number placed in front of an element symbol

How many neutrons does element X have if its atomic number is 21 and its mass number is 95?

How many moles of an ideal gas are in a tank with a volume of 22.9 L at pressure of 14.297 atm at 12°C? (Show work and units)

Carla is making two drinks. She is making one hot chocolate and one chocolate milk. Which best describes the agitation needed to make sure the cocoa powder is mixed in well? Chocolate milk would require more agitation than hot chocolate does.

A container with 0.317 L of water is placed into microwave and is then radiated with electromagnetic energy that has a wavelength of 13.3 cm. The temperature of the water then rose by 74.3 °C.

1. What specifically are you looking for in the IR spectrum to determine if the reaction has given the desired product? 2. What specifically are you looking for in the NMR spectrum to determine if the reaction has given the desired product?

A student has a solution with a pH of 7. The student adds HF, hydrogen floride, to the solution, hoping to increases the pH of the solution. What is wrong with this student's approach? Select one: A. You cannot change the pH of a solution. B.

What is more likely to happen if wetlands are drained?

A) If you weigh a hydrated compound before and after heating it. Do you expect the mass to be more or less than before heating? Explain why. b) How about if you weigh a bag of popcorn before and after heating it.

Define the term relative molecular mass

It took many of the metals several minutes to begin to react. Once the reaction was initiated, several of these metals continued to react quite vigorously.