The atomic and mass numbers for four different atoms are given below. which two are isotopes of the same element?

atom atomic number mass number
a 100 257
b 101 257
c 101 260
d 102 259

a.) a and b
b.) b and c
c.) b and d
d.) c and d

Which term best describes the form sound takes as it travels away from a drum (a- gas)(b-music) ( c-waves) (d-particles

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

Is it safe to take 450mg of diphenhydramine hydrochloride?