calculate the energy of a photon emitted when an electron in a hydrogen atom undergoes a transition from =7 to =1.

How many liters of 60% alcohol solution should be added to 40 liters of a 20% alcohol solution to make a 50% solution?

Alex is the head photographer for the yearbook and the newspaper. she has a large staff of assistant photographers because they need to take pictures at all of the school events. she knows that some of her photographers have better cameras and can take action shots at sporting events, and that some of them are good at taking candid pictures in the hallways. she sets firm deadlines so she has enough time to look through all of the shots and choose the best ones. she gives her photographers constructive feedback to them improve their pictures. respectful enforcer warlord doormat peacemaker

Layer r contains a well-known index fossil that is 100 million years old. based on this information and the principle of superposition, a. layers t and m are older than 100 million years, and layers x and g are younger than 100 million years. b. layers t, m, x, and g are all older than 100 million years. c. layers t and m are younger than 100 million years, and layers x and g are older than 100 million years.