During what phase of the moon can a lunar eclipse occur?

A) new moon

B) first quarter

C) waxing gibbous

D) full moon

The layer of the interior of the sun where the temperature drops from 7,000,000°C to 2,000,000°C

What are the three signs that a chemical change has taken place

The melting of gold is a physical change. why?

5. 1.2 grams of HCl in 75 mL of solution 6. 750 mg of NaCl in 3.5 Liters of solution

What is the mass in grams of na 2 co 3 (s) (molar mass = 105.98 g/mol) that, when dissolved in 125 ml of water, will make a 0.15 m aqueous solution?

What is the rough er connected to

Two students design an experiment to see if pushing or pulling a box across the floor is more effective. The first student pushes the box across the floor a distance of 20 feet and the second student times how long it takes.

15.00 g of NH4HS (s) is introduced into a 500. mL flask at 25 °C, the flask is sealed, and the system is allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if Kp = 0.108 at 25 °C for: NH4HS (s) ⇄ NH3 (g) + H2S (g) ?

Among elements 1-18, which element or elements have the smallest effective nuclear charge if we use the equation zeff=z-s to calculate zeff? check all that apply.

Two clear solutions are placed in separate beakers. The first solution has a pH of 4, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting pH is 5, the second solution must have