Answer:
Metalloids are metallic-looking brittle solids that are either semiconductors or exist in semiconducting forms, and have amphoteric or weakly acidic oxides. Typical nonmetals have a dull, coloured or colourless appearance; are brittle when solid; are poor conductors of heat and electricity; and have acidic oxides.
Explanation:
Algunas acciones viables para utilizar los recursos ambientales de forma racional y con el objetivo de reducir la contaminación son:
- Reducir, reciclar y reutilizar los residuos generados en el hogar.
- Reducir el uso de vehículos de combustión interna.
- No quemes basura al aire libre
- No utilices aerosoles ni frigoríficos que dañen la capa de ozono.
<h3 /><h3>¿Qué importancia tiene la sostenibilidad?</h3>
Es fundamental para la preservación y mantenimiento del medio ambiente y la calidad de vida de las generaciones actuales y futuras. El desarrollo de acciones sostenibles promueve la protección del medio ambiente, los ecosistemas y los recursos naturales.
Por lo tanto, todas las personas e instituciones económicas pueden promover la sostenibilidad a través de prácticas fáciles de ejecutar que ayuden a preservar y proteger el medio ambiente.
Encuentre más información sobre sostenibilidad aquí:
brainly.com/question/23701037
<span>1. Which variable is the independent variable and which is the dependent variable? Density vs. ethylene glycol
The independent variable would be ethylene glycol and dependent variable would be density.
A. A 25-mL volumetric flask with its stopper has a mass of 32.6341 g. The same flask filled to the line with ethylene glycol (C2H6O2, automotive antifreeze) solution has a mass of 58.0091 g. What is the density of the ethylene glycol solution?
Density = 58.0091 - 32.6341 / .025 = 1015 g/L
B. What is the molarity of the ethylene glycol solution, if the mass of ethylene glycol in the solution is 12.0439 g?
Molarity = 12.0439 ( 1 mol / 62.07 g) / 0.025 = 7.8 M</span>
Answer:
Kinetic energy: 
Velocity: 
Explanation:
From the equations of the photo-electric effect,
We know:
Where,
1.
is the Planck's constant which is 
2.
are the frequency of light emitted and threshold frequencies respectively.
3.
is the kinetic energy of the electrons emitted.
By fact, we come to know that the threshold frequency of Zn is 300nm
And also 
Where ,
1. 
is the speed of light 
2.
is the wavelength.
Thus,
Now to find velocity:
Answer:
0.42 g
Explanation:
<u>We have: </u>
pH = 12.10 (25 °C)
V = 800.0 mL = 0.800 L
To find the mass of sodium hydroxide (NaOH) we can use the pH:
![pOH = -log ([OH^{-}])](https://tex.z-dn.net/?f=%20pOH%20%3D%20-log%20%28%5BOH%5E%7B-%7D%5D%29%20)
![[OH]^{-} = 10^{-pOH} = 10^{-1.90} = 0.013 M](https://tex.z-dn.net/?f=%5BOH%5D%5E%7B-%7D%20%3D%2010%5E%7B-pOH%7D%20%3D%2010%5E%7B-1.90%7D%20%3D%200.013%20M)
Now, we can find the number of moles (η) of OH:
![\eta = ([OH]^{-})*V = 0.013 mol/L * 0.800 L = 1.04 \cdot 10^{-2} moles](https://tex.z-dn.net/?f=%5Ceta%20%3D%20%28%5BOH%5D%5E%7B-%7D%29%2AV%20%3D%200.013%20mol%2FL%20%2A%200.800%20L%20%3D%201.04%20%5Ccdot%2010%5E%7B-2%7D%20moles)
Since we have 1 mol of OH in 1 mol of NaOH, the number of moles of NaOH is equal to 1.04x10⁻² moles.
Finally, with the number of moles we can find the mass of NaOH:
<em>Where M is the molar mass of NaOH = 39.9 g/mol </em>
Therefore, the mass of sodium hydroxide that the chemist must weigh out in the second step is 0.42 g.
I hope it helps you!
