Answer:
Empirical formula: BH3
Molecular Formula: B2H6
Explanation:
To solve the exercise, we need to know how many boron atoms and how many hydrogen atoms the compound has. We know that of the total weight of the compound, 78.14% correspond to boron and 21.86% to hydrogen. As the weight of the compound is between 27 g and 28 g, using the above percentages we can solve that the compound has between 21.1 g and 21.8 g of boron, and between 5.9 g and 6.1 g of hydrogen:
100% _____ 27 g
78.14% _____ x = 78.14% * 27g / 100% = 21.1 g boron
100% ______27 g
21.86% ______ x = 21.86% * 27g / 100% = 5.9 g hydrogen
100% _____ 28 g
78.14% _____ x = 78.14% * 28g / 100% = 21.8 g boron
100% _____ 28g
21.86% _____ x = 21.86% * 28g / 100% = 6.1 g hydrogen
So, if the atomic weight of boron is 10.8 g, there must be two boron atoms in the compound that sum 21.6 g. The weight of hydrogen is 1 g, so the compound must have six hydrogen atoms.
The molecular formula represents the real amount of atoms that form a compound. Therefore, the molecular formula of the compound is B2H6.
The empirical formula is the minimum expression that represents the proportion of atoms in a compound. For example, ethane has 2 carbon atoms and 6 hydrogen atoms, so its molecular formula is C2H6, however, its empirical formula is CH3. Therefore, the empirical formula of the boron compound is BH3.
Answer:
The tank with O₂ weighs more.
Explanation:
We can find the mass of gas using the ideal gas equation.

Considering the pressure (P), volume (V), temperature (T) and ideal gas constant (R) are the same, we can establish that:
m ∝ M
The mass is directly proportional to the molar mass. The molar mass of O₂ (32 g/mol) is higher than the molar mass of N₂ (28 g/mol). Therefore, the tank with O₂ weighs more.
The motion causes day and night because the earth is constantly spinning on it's axis.
Answer:
Q = 28.9 kJ
Explanation:
Given that,
Mass of Aluminium, m = 460 g
Initial temperature, 
Final temperature, 
We know that the specific heat of Aluminium is 0.9 J/g°C. The heat required to raise the temperature is given by :

So, 28.9 kJ of heat is required to raise the temperature.
Answer:
Weathering, Erosion
Explanation:
Plants and animals can be agents of mechanical weathering. The seed of a tree may sprout in soil that has collected in a cracked rock. As the roots grow, they widen the cracks, eventually breaking the rock into pieces. Over time, trees can break apart even large rocks.
Tree root systems have a handful of large roots that branch out into a network of smaller roots that often extend out far beyond their branches do. These root systems prevent erosion by holding the soil in place and improving drainage which helps water get absorbed into the soil instead of just running over the top.
Hope this helps
All the love, Ya boi Fraser :)