Why do scientists sometimes discard theories?

According to "Black Hole Beginnings," what causes the end of a star?

The sum of the protons and neutrons in an atom is its A. charge. B. atomic energy. C. atomic mass.

Could you separate a mixture of salicylic acid and aspirin by acid-base extraction? briefly justify your answer.

When pellets of NaOH (s) are added to a flask of water, it is observed that the temperature of the water increases as the pellets dissolve. Which of the following claims about the observed dissolution of NaOH (s) in water is most accurate?

You are a fireworks maker. For the safety of the workers producing the material you want to reduce the rate of reactions to prevent explosions. What can you do to reduce the reaction rate?

What ionic bond occurs between what particles? A. Two Negative Ions B. A positive and negative ion C. Two positive ions D. Two neutral atoms

Which of the following are good traits of a hypothesis? it will be able to be tested it can predict an outcome it will explain the observations all of these

What is the mass of a box of nails

In a phase change of water between the liquid and the gas phases, 770.1 kJ of energy was released by the system. What was the product, and how much of it was formed in the phase change? (dа ta: H₂O (l) → H₂O (g) ΔH = 44.01 kJ/mol.) A.

Explain the problem surrounding the ammonia-making process in terms of chemical equilibrium. Chemical equation for producing ammonia: N2 + 3H2 ⇌ 2NH3 + energy