The range for em radiation should be a range of 50 yards hope this help's. <span />
Answer:
See explanation
Explanation:
Crystals can be made from methanol by recrystallizing the plant extract from methanol.
The methanol/water system is heated rapidly using a hot plate and the plant extract dissolves in the heating solution until a clear solution is obtained.
The solution is now cooled rapidly. The interior of the flask used for the re crystallization may even by scratched to assist the quick formation of crystals. Large crystals of plant compounds may be obtained using this method. This process should be carried out in a fume hood because of the toxicity of methanol.
The energy change if 84.0 g of CaO react with excess water is 98KJ of heat is released.
calculation
heat = number of moles x delta H
delta H = - 65.2 Kj/mol
first find the number of moles of CaO reacted
moles = mass/molar mass
the molar mass of CaO = 40 + 16= 56 g/mol
mass = 84 g
moles therefore = 84 g/56 g/mol =1.5 moles
Heat is therefore = 1.5 moles x -65.2 = - 97.8 Kj = -98 Kj
since sign is negative the energy is released
The mass of water decomposed to produce 50 g oxygen has been 56.28 g. Thus, option D is correct.
The reaction for the decomposition of water has been:
From the balanced equation, 2 moles of water decomposes to form 1 moles of hydrogen and 1 mole of oxygen.
The mass of oxygen produced has been 50 g. The moles of oxygen has been given by:
The moles of oxygen has been:
The moles of oxygen produced has been 1.5625 mol.
The moles of hydrogen decomposed has been given from the balanced chemical equation as:
The moles of hydrogen decomposes has been 3.125 mol.
The mass of hydrogen decomposed has been given by:
The mass of water decomposed to produce 50 g oxygen has been 56.28 g. Thus, option D is correct.
For more information about moles produced, refer to the link:
brainly.com/question/10606802
Answer:
a. similar properties
Explanation:
In a given column of the periodic table, the elements have similar properties.
A column on the periodic table is known as a group or family. The group is a vertical arrangement of elements on the periodic table.
Elements in the same group have the same number of valence electrons after their group number.
For example, all the elements in group 1 have one valence electron. Those in group 2 have 2 valence electrons.
The valence electrons of an atom determines its chemical properties. So, all elements in the same group have the same chemical properties.
