Lo 2.7 The different grades of paper are reprocessed separately at the paper mill.
2 8 The paper is chopped into small pieces and mixed with hot water to form a
pulp.
3
ACTIVITY 3
Match the NAME with the correct DESCRIPTION. Complete the ANSWER by writing
the correct letter.
(5)
NAME
1. Landfills
2. Pulping
3. Crude oil
ANSWER DESCRIPTION
A. The containers or wrappers used to hold or contain
products
B. The ability to break down naturally into simple,
harmless substances
C. Large holes in the ground in which waste products are
buried
D. A fossil fuel, used to make petrol, plastic, paraffin and
other products
E. Lightweight plastic used for packaging for example
takeaway holders that can be disposed after use
F. Wood chips are broken down into thin fibres
G. Tree logs are cut into small chips
4. Chipping
5. Packaging
6. Polystyrene
7 Biodegradable​

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

c. is the answer

by love gaming