Question 7 Which of the following discoveries led to the development of the quantum mechanical model?
A electrons occupied different energy levels around the nucleus
B
atoms of gases combined to form compounds in whole-number ratios
Cmost alpha particles passed through gold foil without hitting matter
D cathode rays could be bent by a magnetic field

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

Which factor is likely to impact the possible number of compounds ?

What is the molarity of the solution produced when 145 g of nacl is dissolved in sufficient water to prepare 2.75 l of solution?