What is the most important question to ask to determine wheatear a change is physical or chemical

Cindy made tea. She started with 300 grams of water at 20 degrees Celsius. She transferred 18,000 calories to the water. What was the final temperature of the water?

What is the purpose of subscripts in chemical formulas?

How many atoms or moles of each element are on either side of the yield arrow? Is this equation balanced? 2Na+H2O---> NaOH+2H2

Critique you overhear someone say, I'm going to nuke it when referring to cooking food in a microwave oven. Explain why this terminology is in correct.

Demonstrate In A Brief Paragraph How The Search To Explain Planetary Orbits Exemplifies The Scientific Method

If the human body were a car, glucose would be:

Which part of the circulatory system contains blood rich in carbon dioxide (1) arteries (2) alveoli (3) veins (4) capillaries

Andrea was watching her brother in the ocean and noticed that the waves were coming into the beach at a frequency of 0.571429 Hz. How many waves hit the beach in 28 s? Answer in units of waves.

How many chloride ions are needed to cancel the 2 + charge of magnesium in magnesium chloride?

How many liters of air are in: A) a room that measures 10.0 ft * 11.0 ft and has an 8.00 ft ceiling? B) a room that measures 11.0 ft x 11.0 ft and has a 10.0 ft ceiling? 1 in. = 2.54 cm (exactly); 1 L = 103cm3