A sample of Strontium-90 has a Half-Life of 28.1 years. How long will it take for a sample to decay to 12.5% of its original mass?
A sample of Ge-66 (Half-Life = 2.5 hours) sat for 10 hours and only 5 grams remain. What wcw
the mass of the original sample?
I
Element X is a Radioisotope. If a 100-kg sample of Element X decays to 12.5 kg in 1 day, what
is the Half-Life of Element X in hours?
+
Strontium-90 (Half Life = 28.1 years) is used as a Radioactive Tracer in Medical and Agricultural
Studies. How many atoms out of a 1.68 x 1023 atom sample will remain undecayed after 56.2
years?
What percentage of a 900-gram sample of Potassium-37 (Half-Life = 1.23 seconds) exists after
6.15 seconds?

yes they ca   is ur ansswerrr

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g

gold is my favorite solid.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.