Jiskhaa

Most popular questions and responses by Jiskhaa
1. Maths

If tan theta= 1/5 Simplify tan(540-theta) In the unit circle do I have to go clockwise or anti-clockwise from the fourth quadrant? Please help is needed for this

2. Mathematics

The value of a certain fraction becomes 1/5 if one is added to its numerator. If one is taken from its denominator, its value becomes 1/7. Find the fraction by setting up a pair of simultaneous equations and solving them

3. Maths

A closed rectangular wooden box has external dimensions 17x12x10. If the wood is 1cm thick, calculate the volume of wood required to make it. (All measurements are in Cm)

4. Chemistry

List commercial, everyday products whose manufacture starts with ethylene or ethene. I have already listed down plastic bags and milk containers. Could petrol be one of them?

5. Maths

If Q(x)=x^2 for x less than or equal to 1 =ax+b for 1

6. Maths

Calculate the number of litres of water delivered per minute by a pipe with cross-sectional area 15 square centimetres, if the water passes through the pipe at an average speed of 30cm/s (second) P.S. Working out please

7. Maths

A rectangualr metal sheet is 32m long, 16m wide and 12mm thick. Eight circular holes, each of diameter 3m are cut in the sheet, so that none of the holes overlap. Calculate the volume of metal remaining, correct to 3 decimal places (Take pi=3.142) P.S.

8. Maths

The earth is approximately a sphere of average diameter 12740km. The smallest of the planets is Mercury, also spherical, with average diameter 4840km. Determine what percentages (to the nearest hundredth) the volume and surface area of Mercury are of those

9. Chemistry

If 1 mol L of 2.0 mol L hydrochloric acid is diluted to form a solution with concentration 0.2 mol L, A. What is the final volume? B. how much water must be added to the original acid? Use C1V1= C2V2, thanks in advance

10. Chemistry

Calculate the molarity of the solutions made by dissolving the following amounts of solute in water and making the volume up to the stated value. 5.0mol nitric acid in 2.0L Do I just find the molarity for nitric acid only, because when I write out the

11. Chemistry

During the phase of condenstion, is heat being absorbed from surroundings or released into surroundings! I think it is being released into surroundings! Thanks

12. Maths

If (x-k, where k is integral, is a factor of the polynomial P(X)=2x3-3x2-12x-7, what possible values may k have? Working out please! I only have 7 as a possible answer need one more

13. Trig

Find the exact values of sin 2 theta, cos 2 theta and tan 2thea using the double angle formula sin theta = 3/4 , pi/2 < theta < pi

14. Maths

Find the equation of the locus of the point P(x,y) which moves so that it's distance from the point (0,3) is equal to its distance from the line y=-3 Show that the point (-6,3) lies on the locus Please help me with thisand also show working out

15. Maths

X squared-(k+3)x+4k=0 Please help me find the value of k for which there are equal roots but of opposite sign Working out please thanks

16. Maths

M squared is greater than or equal to 36 How to find m I only have one set of answers for m and that is m is greater than or equal to 6 How to find the second set? Working out please

17. Chemistry

An impure sample of substance X melts at about 113 degress. Which of the substances could be X and state y Resorcinal 111 degrees Catechol 105 Nitrophenol 114 Butanamide 115 I think it is either catechol or resorcinol because as stated the higher the

18. Chemistry

Which of the following metals would be expected to have the most unstable salts? a) sodium b) zinc c) tin d) silver Please define for me what 'unstable salts' are please?

19. Chemistry

Discuss the effect of the 'extra' hydroxyl groups on the physical properties of diols and triols, compared to alkanols that have only one hydroxyl group. HINT: Consider the polar nature of the hydroxyl group Really need help for this!!!