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Molodets [167]
3 years ago
10

Which action is the best example of a direct observation

Chemistry
2 answers:
kiruha [24]3 years ago
5 0

The answer is D Determining the seal population of an island by counting seals in 10 square meters of the island on e2020

luda_lava [24]3 years ago
3 0

Since you didn't have any extra information about the question I'll be presenting an example from my own textbooks that I've used.

An example of a direct observation is listening to a cricket chirp at night, and counting the number of chirps per minute.

Direct Observation is where the evaulator watches the subject in their usual habitat without disrupting or altering it.

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When a 3.80 g sample of magnesium nitride (MW 101g/mol) is reacted with 3.30 g of water, 3.60 g of MgO is formed. What is the pe
lianna [129]
  The  percent   yield  of  this   reaction  is  calculated  as  follows
  Mg3N2  +  3H2O  =2NH3  +  3Mgo

  calculate  the   theoretical  yield,
moles=mass/molar  mass
moles Mg3N2=  3.82  g/100g/mol=  0.0382  moles(limiting  regent)

moles of  H2o=  7.73g/18g/mol  = 0.429  moles ( in  excess_)

by  use   of  mole  ratio   between  Mg3N2  to  MgO  which  is  1:3   the    moles  of MgO =  0.0382  x3  = 0.1146  moles
mass =moles  x molar  mass

the  theoretical  mass  is therefore =  0.1146mole  x  40  g/mol  =  4.58 grams

The %  yield  =  actual  mass/theoretical  mass  x1000

=  3.60/4.584  x100=  78.5%
3 0
3 years ago
Read 2 more answers
3.
LenKa [72]

Answer: 23 g

the mol of Fe is 11,5/56 = 23/112 (mol)

the mol of CO is \frac{2,63.10^{24} }{6.10^{23} }= \frac{263}{60} (mol)

we have:

Fe2O3 + 3CO => 2Fe + 3CO2

23/112    69/112     23/56

=> the mol of Fe is 23/56 mol

=> the mass of Fe is 23/56.56 = 23 (g)

Explanation:

4 0
2 years ago
What is the result of adding 2.5 × 10³ and 3.5 × 10²?
Elanso [62]

Answer:

A

Explanation:

It is correct please I hope it helps! :)

7 0
3 years ago
Read 2 more answers
Which part of the atom takes up the most space
Ivan

The part of the atom that takes up the most space is the amount of electrons

7 0
2 years ago
What is the percent by mass of nahco3 in a solution containing 10 g of nahco3 dissolved in 400 ml of h2o?
Marat540 [252]
Answer is: the percent by mass of NaHCO₃ is 2,43%.
m(NaHCO₃) = 10 g.
V(H₂O) = 400 ml.
d(H₂O) = 1 g/ml.
m(H₂O) = V(H₂O) · d(H₂O).
m(H₂O) = 400 ml · 1 g/ml.
m(H₂O) = 400 g.
m(solution) = m(H₂O) + m(NaHCO₃).
m(solution) = 400 g + 10 g.
m(solution) = 410 g.
ω(NaHCO₃) = 10 g ÷ 410 g · 100%.
ω(NaHCO₃) = 2,43 %
7 0
3 years ago
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