Answer:
That unknown substance is water
Explanation:
Answer:
True
Explanation:
the machine shown in figure 9.9 is called a wheele and axle. It's a form of lever. the effort arm can rotate in a complete circle, which is the center of the axle.
Answer:
B. Particles of matter have spaces between them.
Explanation:
The particle nature model of matter is an model used to explain the properties and nature of matter. The statements of the particle nature model of matter are as follows :
1. Matter is made of small particles of atoms or molecules.
2. The particles of matter have space between them. The spaces between the particles are least in solids as they are closely packed together but are greatest in gases whose particles are far apart from each other.
3. The particles of matter are in constant motion at all times. Solids particles are not free to move due to strong molecular forces between the particles, but are constantly vibrating in their mean positions. Liquid particles free to move due to lesser molecular forces while gas molecules which have negligible intermolecular forces have the greatest ability to move.
4. The particles of matter are attracted to each other by intermolecular forces. These forces are greatest in solids and least in gases.
The correct option is B.
Answer:
[Na₂CO₃] = 0.094M
Explanation:
Based on the reaction:
HCO₃⁻(aq) + H₂O(l) ↔ CO₃²⁻(aq) + H₃O⁺(aq)
It is possible to find pH using Henderson-Hasselbalch formula:
pH = pka + log₁₀ [A⁻] / [HA]
Where [A⁻] is concentration of conjugate base, [CO₃²⁻] = [Na₂CO₃] and [HA] is concentration of weak acid, [NaHCO₃] = 0.20M.
pH is desire pH and pKa (<em>10.00</em>) is -log pka = -log 4.7x10⁻¹¹ = <em>10.33</em>
<em />
Replacing these values:
10.00 = 10.33 + log₁₀ [Na₂CO₃] / [0.20]
<em> [Na₂CO₃] = 0.094M</em>
<em />
The movement of rock pieces and other materials on earth's surface is called Weathering
