Answer:
10.8 days (3 sig.figs.)
Explanation:
All radioactive decay is 1st order decay defined by the expression A = A₀e^-kt
which is solved for time of decay (t) => t = ln(A/A₀) / -k
A = final weight = 1.0 gram
A₀ = initial weight = 16.0 grams
k = rate constant = 0.693/t(1/2) = 0.693/2.69 days = 0.258 days⁻¹
t = ln(1/16) / -0.258da⁻¹ = (-2.77/-0.258) days = 10.74646792 days (calculator)
≅ 10 days (1 sig. fig. based on given 1 gram mass)
Answer:
The physical and chemical properties of the product do not match the properties of the reactant.
Explanation:
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible
These changes occur due to chemical reactions
These may not be observed with naked eye
Example:
Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood
Boiling of egg: that change the chemical composition of protein in the egg .
The reaction of Hydrogen and oxygen:
H 2 (g) + O 2 (g) -------------------------------------> 2H 2O (l)
The reaction between sugar and oxygen form a product which is different from the reactant that's why it indicate the occurrence of chemical reaction.
While in case of physical changes just state of matter are changed. Properties remain same.
Answer:
sugar and oxygen
Explanation:
In photosynthesis, solar energy is harvested as chemical energy in a process that converts water and carbon dioxide to glucose. Oxygen is released as a byproduct.
Oxidation state of Pb in PbO2 is +4.
Oxidation state of Pb in PbCl2 is +2.
Oxidation state of Pb in Pb2O is +1.
Oxidation state of Pb in Pb4O3 is +6/4.
Hence option A. PbO2 is correct.
Hope this helps, have a nice day!
Sedimentary rocks don't necessarily make fossils. Although when animals die on top of the rocks and are never moved, blown away, etc they can get trapped under the growing rock. Which is why fossils are often found in sedimentary rocks.
