You need to make 200ml of a 2% agarose gel in a buffer solution (1x tae) how many grams of agarose do you need?

 The number  of grams of  agarose that  you need  to make 200 ml  of 2% agarose gel  is  4 grams

  calculation
number of   grams  is calculated  using   M/v  x100 =% m/v  formula
  M (mass)  =?
V(volume) = 200 ml
%(M/V)  = 2%

convert  the  2 % M/V   into fraction  = 2/100  

then  substitute the values into the  equation

= M/200 ml  = 2/100

multiply both side by 200

M is therefore  = 2/100 x200

M=4 grams