Answer:
he predicted the properties from known elements above and belws the unknown in the same group
Explanation:
What allowed Mendeleev to make predictions of undiscovered elements
He realized that an element on this table with one known element above it and one known element below it had to have properties between the two known elements
How did Mendeleev predict gallium and germanium?
Based on gaps in the periodic table Mendeleev deduced that in these gaps belonged elements yet to be discovered. Based on other elements below and above in the same group he predicted the existence of eka-aluminum, eka-boron, and eka-silicon, later to be named gallium (Ga), scandium (Sc), and germanium (Ge).
Answer:
the original concentration of A = 0.0817092 M
Explanation:
A reaction is considered to be of first order it it strictly obeys the graphical equation method.

where;
k = the specific rate coefficient = 3.4 × 10⁻⁴ s⁻¹
t = time = 5.0 h = 5.0 × 3600 = 18000 seconds
a = initial concentration = ???
a - x = remaining concentration of initial concentration at time t = 0.00018 mol L⁻¹







a = 0.0817092 M
Thus , the original concentration of A = 0.0817092 M
Answer: There are 0.5 grams of barium sulfate are present in 250 of 2.0 M
solution.
Explanation:
Given: Molarity of solution = 2.0 M
Volume of solution = 250 mL
Convert mL int L as follows.

Molarity is the number of moles of solute present in liter of solution. Hence, molarity of the given
solution is as follows.

Thus, we can conclude that there are 0.5 grams of barium sulfate are present in 250 of 2.0 M
solution.
Answer:
Explanation:
q= mc theta
where,
Q = heat gained
m = mass of the substance = 670g
c = heat capacity of water= 4.1 J/g°C
theta =Change in temperature=(
66-25.7)
Now put all the given values in the above formula, we get the amount of heat needed.
q= mctheta
q=670*4.1*(66-25.7)
=670*4.1*40.3
=110704.1
B . microscope
this is the answer .