Proton, the gold foil experiment indicated that the nucleus has a positive charge.
Explanation:
Tc - 99 is technetium 99.
It is a radioactive element that decays spontaneously. It has a half-life of 211,000 years and decays to stable ruthenium.
- On the periodic table, it has an atomic number of 43;
Mass number = 99
Atomic number = number of protons = number of electrons in atom
Number of protons in Tc is 43
electron is 43
Mass number = number of protons + number of neutrons
Number of neutrons = mass number - number of protons = 99-43 = 56
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Answer:
it can last for 30 minutes
Explanation:
because it is very good at giving off heat, extothermal heat can last for quite a while.
Step 1 - Discovering the ionic formula of Chromium (III) Carbonate
Chromium (III) Carbonate is formed by the ionic bonding between Chromium (III) (Cr(3+)) and Carbonate (CO3(2-)):
Step 2 - Finding the molar mass of the substance
To find the molar mass, we need to multiply the molar mass of each element by the number of times it appears in the formula of the substance and, finally, sum it all up.
The molar masses are 12 g/mol for C; 16 g/mol for O and 52 g/mol for Cr. We have thus:
The molar mass will be thus:
Step 3 - Finding the percent composition of carbon
As we saw in the previous step, the molar mass of Cr2(CO3)3 is 284 g/mol. From this molar mass, 36 g/mol come from C. We can set the following proportion:
The percent composition of Carbon is thus 12.7 %.