How do chemists count the number of representative particles in a substance?

Pls! plant cells and animal cells were observed under a microscope. the characteristics of two cells are listed below. cell p: does not capture sunlight cell q: has cytoplasm but no chloroplast which statement about the two cells is correct? cell q also has a cell wall. cell q also has large vacuole. cell p also has a large vacuole. cell p also has a cell membrane.

20 pts ‼️ an unmanned spacecraft travels to mars. mars has a lower strength of gravity than earth. where in the image is the spacecraft’s weight the greatest?

When a device is used in a circuit in which the voltage is 81 v the current flowing through the device is 3 a what is the resistance of the device