Several centimeters of lead. Gamma rays have the highest penetrating power and therefore need a thick layer of something, in most cases lead, to prevent penetration. (This is why if you have ever go to the dentist they put a heavy thing on you made of lead, to prevent the penetration of gamma rays that can destroy your most important organs).
Answer:
3 Shells
Explanation:
2 electrons in shell one, 8 in shell two and only 1 in shell three.
Mg(NO3)2 => <span>Magnesium nitrate
hope this helps!</span>
Answer:
What is the question needing to be answered?
Explanation:
Usually with a scientific hypothesis, you ask the question in an if, then statement. For example: If it rains outside, then the ground will be wet. It's kind of like a cause and effect statement.
Answer:
We need 1.1 grams of Mg
Explanation:
Step 1: Data given
Volume of water = 78 mL
Initial temperature = 29 °C
Final temperature = 78 °C
The standard heats of formation
−285.8 kJ/mol H2O(l)
−924.54 kJ/mol Mg(OH)2(s)
Step 2: The equation
The heat is produced by the following reaction:
Mg(s)+2H2O(l)→Mg(OH)2(s)+H2(g)
Step 3: Calculate the mass of Mg needed
Using the standard heats of formation:
−285.8 kJ/mol H2O(l)
−924.54 kJ/mol Mg(OH)2(s)
Mg(s) + 2 H2O(l) → Mg(OH)2(s) + H2(g)
−924.54 kJ − (2 * −285.8 kJ) = −352.94 kJ/mol Mg
(4.184 J/g·°C) * (78 g) * (78 - 29)°C = 15991.248 J required
(15991.248 J) / (352940 J/mol Mg) * (24.3 g Mg/mol) = 1.1 g Mg
We need 1.1 grams of Mg
