# Posts by yuni

Total # Posts: 26

**bio lab**

what should i labeled on giant chromosome slide? -things that should have on that chromosome.

**chem lab**

KMn04 with iron(II) ammonium sulphate hexahydrate-redox titration. 1-what is the purpose of adding H2SO4 to iron sample before the titration? 2-why is there no indicator used to determine the end point for this titration? 3-suggest another possible oxidising agent and reducing...

**chem**

the common metallic elements have been invetigated for their relative reactivities and have been arranged into what is called electromotive series. Explain the series in terms of choosing the suitable electrode in setting up an electrochemical series.

**chem lab**

does the voltaic cell(in exp) must be the same with the standard cell that we calculated based on the formula?

**chem**

is the answer 1392 s?

**chem**

The reaction AB(aq)->A(g)+ B(g)is second order in AB and has a rate constant of 0.0282 M^{-1} s^{-1} at 25 Celsius. A reaction vessel initially contains 250 mL of 0.105 M AB which is allowed to react to form the gaseous product. The product is collected over water at 25 ...

**bio**

thanks

**bio**

are blood pressures have differences between genders?explain your answer. -from what i know, women have lower risk to get high blood pressure but for the range of normal blood pressure, i think there is no differences. pls correct me if i wrong and if im right can i know the ...

**phy**

i'm sorry. the electric field are from A to B. dear drwls,you didn't answer my question. i know about the concept but why the v is negative? or how can it be proven mathematically by the formula?.

**phy**

potential difference=40v b2n plate A & B. find work done if q=+3C from a) B to A b) A to B *i already know the ans but i need the explanation for the formula. -this is my work a)w=-qv b)-120J =-3(-40) =120 J what i want to ask is: 1-why must we add - sign for v is not that if ...

**math**

if a & b are perpendicular vectors, show that a)(a+2b).(a-b)=|a|^2-2|b|^2 b)(a+b).(a-b)=|a|^2+|b|^2 *how to show it?just multiply it?if yes where does||come from? does||show that it should be a value?

**math**

Find the interior angle formed by points A(1,5,3) , B(-2,3,7) , C(3,2,5). does this mean i need to find all the 3 angles of triangle?

**math**

the position vectors of the point A,B & C respect to O are a=3i-2j+4k, b=i+3j-4k, c=-2i+5j-3k. Find a)the angle between a+b and a-b b)lamdar if vector a is perpendicular to b+lamdar k.

**math**

prove cos(x+y) / cos(x-y) = (1-tan x tan y)/(1+tan x tan y)

**chem**

rate=k[A2][B2]^2. by how much would the rate change if: i) [A2] is doubled? ii) [B2] is halved? *does the rate change equal with k?

**chem**

the atom of element A has 2 electrons in its highest energy level N. a)what is the special name given to elements in the same gp as A? i answered as alkali earth metal because the valence electron is 2. am i right?

**chem**

150 cm3 0.24 M naoh solution react with excess al(no3)3, calculate the mass of saodium aluminate produced. al(no3)3 + 4naoh -> naalo2 + 3 nano3 +2h20 i got 0.738g.. is my answer correct? if im wrong could u show me the calculation?

**biology lab**

im sorry but b4 this i already seacrh at the internet but i didn't found what i want. so i hope there will be another answer coming on.

**biology lab**

how to know from the experiment if the oxygen produced as a result of carbon fixation or electron transport? my experiment result show that average bubble/min for tap water is 4.7 while NaHCO3 is 1.8.

**biology lab**

-rate of photosyhthesis in presence of light intensity & CO2. ~A : sodium bicarbonate in darkness pH b4 xperiment-9 " @ 20 min- 8 " 60 min- 8 ~B: sodium bicarbonate in room light pH b4 xperiment-9 " @ 20 min-9 " 60 min-8 ~C: sodium bicarbonate 20 cm from ...

**biology**

what is the original color of Phenolphthalein solution? pink or colourless?

**math**

can any1 plz answer this question.

**math**

A piece of wire of length 240 cm is bent into the shape of trapezium where the eqtn is = 13x+13x+y+y+24x. Find the value of x and y for which A is maximum, hence find the maximum area. a. express y in term of x b. show that the area A cm^2 enclosed by the wire is given by ...

**math**

the volume of an cylindrical can with a radius r cm and height h cm is 128000 c^3, show that the surface area of the can is A=2(22/7)r^2 + 246000/r. Find the value for r to minimize the surface area. *i know what the quest. ask but i do not know how to apply it.

**math**

a liquid form of penicillin is sold in bulk at a price of $ 200 per unit.If the total cost for x unit is C(x)=500000+80x+0.003X^2 and the production capacity is at most 30000 at a specified timed, how many of the penicillin must be manufactured and sold in that time to ...

**Chemistry Lab**

if i get 4 % of yield in the experiment of chemical reactions of copper and percent yield. Is there a possibility the experiment wa success? ~in my opinion it was success because ou theoritical yield is below 100 % ~i just need some opinion.

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