Explain how scientists know the composition of the bottom layer of the crust? o Scientists can find evidence when volcanoes erupt.
Scientists look at the bottom of the ocean for evidence.
Scientists use satellite pictures.
o Scientists have collected evidence from meteoroids.

What is the ima of the 1 st class lever in the graphic given? 2 3 0.5

An atom of sodium-23 (atomic number = 11) has a positive charge of +1. give this information, how many electrons does it have? how many proteins and neutrons does this atom have

Balance and in which category does it fit in? single or double displacement or synthesis or decomposition? (a) k2 o → k + o2 (b) na + i2 → nai (c) cu(no3 )2 + naoh → cu(oh)2 + nano3 (d) kclo3 → kcl + o2 (e) ca(no3 )2 + hbr → cabr2 + hno3 (f) sn(oh)2 → sno + h2 o (g) p4 + n2 o → p4 o6 + n2 (h) fe + al2 (so4 )3 → feso4 + al (i) alcl3 + na2 co3 → al2 (co3 )3 + nacl (j) c3 h6 + o2 → co2 + h2 o