The carbon atom is sometimes listed as carbon-12 and sometimes as carbon-14 what does this mean? plz this is urgent

Where do homologous chromosomes exchange genetic material through crossing over?               a.  chlorophyll    b.  centrosomes    c.  centromeres    d.  chiasma

My question says on my assignment. read the following scenarios and decide which of the properties of life are being described. the first one is. katherine stopped on the way to school to grab some donuts. 2. because a dog cannot sweat, it has to pant in order to stay cool. 3. an elephant trun had no bone but 4,000 muscles. i have no idea what i am supposed to anwer. i can't find the answer in my notes or book that i can understand anyway

Anurse is in the dining room and overhears a new nurse tell a client with body dysmorphic disorder that she's much too thin and must eat more before she can go home. the client bursts into tears and runs out of the dining room. what is the best way for the nurse to address this situation?