Top answers

In a bag of 72 red and green marbles, 5/9 are green. What is the number of red marbles in the bag?

72 cards5/9 are green = 72/(5/9) = 40 green marbles72 - 40 = 32 red marbles
VS
Answered by Venn S. • Maths tutor
4071 Views

The student did another experiment using 20 cm3 of sodium hydroxide solution with a concentration of 0.18 mol/dm3 . Relative formula mass (Mr) of NaOH = 40 Calculate the mass of sodium hydroxide in 20 cm3 of this solution.

20/1000 *0.18 final answer 0.144 Answer must be explained in person. It is very difficult to explain in writing.
SG
Answered by Saranya G. • Chemistry tutor
5317 Views

Why is there a significant difference between the radii of first and second row transition metals, where as no difference (or even a decrease) is observed between the second and third rows?

The answer stems from the lanthanide (or lanthanoid) contraction. In more detail, there is a steady decrease in the radii of atoms from Lanthanum through to Lutetium, despite the associated increase in the a...
IB
Answered by Ioannis B. • Chemistry tutor
3369 Views

Why do ionisation energies have a general increase across periods?

Ionisation energy is the energy required for one mole of gaseous atoms to lose one mole of electrons, hence forming one mole of gaseous ions.The ionisation energies for elements increases across the period b...
AP
Answered by Anna P. • Chemistry tutor
3661 Views

Why is the nos form of 'jugar', spelt 'jugamos' and not 'juegamos'

The nos form of 'jugar' is spelt 'jugamos' and not 'juegamos' because it is a radical changing verb. This means that the stem of the verb does not stay the same as it would with regular verbs, such as comer ...
HB
Answered by Hannah B. • Spanish tutor
7054 Views