rosie

(cos^4θ-sin^4θ)/cos^2θ = 1-tan^2θ

Can someone show me step by step how to solve this please?

A buffer solution is made when 1.50 g of sodium hydroxide are added to 1.00 dm3 of a 0.150 mol dm–3 solution of a weak acid HA.

For HA, the acid dissociation constant, Ka = 1.79 × 10−5 mol dm−3.

Calculate the pH of this buffer solution.

1) Find the values of k for which the equation x²+kx+16=0 has real roots.

2) Find the values of m for which the equation x²+2mx+9=0 has no real roots

3) Find the values of p for which the equation px²+2x+p=0 has real and distinct roots

Or how does the ingredients used in panna cotta make it an Italian dish?

Do any particular religious or cultural celebrations in Italy influence people's food choices?

Aluminium reacts with iron (III) oxide, Fe₂O₃, to give iron metal and aluminium oxide, Al₂O₃.

The a) part of the question was to find the balanced equation of this reaction - which is:

2Al + Fe₂O₃ = 2Fe + Al₂O₃

b) In an experiment, 32.0g of iron (III) oxide was reacted with 16.2g of aluminium. Which of the two reactants is the limiting reactor?

Ans: In the reaction, the mole ratio of Al to Fe₂O₃ is 2:1, so 0.600 mol of Al could react with 0.300 mol of Fe₂O₃. There is only 0.200 mol available, though, so the Fe₂O₃ is the limiting reactant and Al is in excess.

So, what is the maximum mass of iron that could be collected at the end of this experiment?