Round off each of the following numbers to two significant figures:

]The image shows groundwater zones.

11111nata11111 [884]

Answer:

C.) 3 is the correct answer

7 0

3 years ago

Read 2 more answers

How does a concave lens differ from a convex lens? A) A convex lens is another way to describe a plane mirror; a concave lens is

elixir [45]

<h3><u>Answer;</u></h3>

C) A convex lens has a thick center and thin edges; a concave lens has a thin center and thicker edges.

<h3><u>Explanation;</u></h3>

Convex lens refers to the lens which merges the light rays at a particular point, that travels through it, while a concave lens can be identified as the lens which disperses the light rays around, that hits the lenses.
A convex lens is thicker at the center, as compared to its edges, while a concave lens is thinner at the center as compared to its edges.
A concave lens is thicker at the edges than in the middle and spreads light rays apart producing an image smaller than the actual object. A convex lens on the other hand, is thinner at the edges and thicker towards the center, that is they are bent towards a central point.

7 0

3 years ago

Read 2 more answers

Organic molecules are defined as chemical compounds that contain ______ in distinct ratios and structures.

OLga [1]

Answer:

The answer is: <em>carbon</em>

Explanation:

Organic molecules contain the chemical element carbon (C) in its structure. In this type of molecules, carbon is usually bonded to hydrogen (H), oxygen (O) and, with less frecuency, nitrogen (N). Therefore, in these molecules, carbon forms simple, double and triple bonds with itself. Examples of organic molecules that are very important in biology are carbohydrates, lipids, proteins and nucleic acids.

8 0

3 years ago

Two solutions, initially at 24.60 °C, are mixed in a coffee cup calorimeter (Ccal = 15.5 J/°C). When a 100.0 mL volume of 0.100

yulyashka [42]

Answer:

ΔH = -59.6kJ/mol

Explanation:

The reaction that occurs between Ag⁺ and Cl⁻ ions is:

Ag⁺ + Cl⁻ → AgCl(s) + ΔH

To find ΔH we need to obtain moles of reaction and heat released in the reaction because ΔH is defined as heat released per mole of reaction.

<em>Moles of reaction:</em>

Moles of Ag⁺ and Cl⁻ added are:

Ag⁺: 0.100L * (0.100mol / L) = 0.01moles

Cl⁻: 0.100L * (0.200mol / L) 0 0.02 moles

That means limiting reactant is Ag⁺ and moles of reaction are 0.01 moles

<em>Heat released:</em>

To find heat released we must use coffe cup calorimeter equation:

Q = C*m*ΔT

<em>Where C is specific heat of solution (4.18J/g°C), m is the mass of solution (200g because there are 100 + 100mL = 200mL and density of solution is 1g/mL) and ΔT is change in temperature (25.30°C - 24.60°C = 0.70°C).</em>

Replacing:

Q = C*m*ΔT

Q = 4.18J/g°C * 200g * 0.70°C

Q = 585,2J

Is total heat released.

The calorimeter absorbs:

15.5J / °C * 0.7°C = 10.85

Thus, when 0.01 moles reacts, 585.2J + 10.85 = 596.05J are released (Heat released is heat abosrbed by calorimeter + Heat absorbed by water) and ΔH is:

ΔH = 596.05J / 0.01 moles =

ΔH = 59605J / mol =

<em>As heat is released, ΔH < 0.</em>

6 0

3 years ago

Complete the equation to show how hydrofluoric acid, HF, acts as a Brønsted-Lowry acid in water. Balanced equation:

shepuryov [24]

Answer : The balanced equation is,

$HF+H_2O\rightleftharpoons H_3O^++F^-$

Explanation :

According to the Bronsted Lowry concept, Bronsted Lowry-acid is a substance that donates one or more hydrogen ion in a reaction and Bronsted Lowry-base is a substance that accepts one or more hydrogen ion in a reaction.

The balanced chemical reaction will be,

$HF+H_2O\rightleftharpoons H_3O^++F^-$

In this reaction, hydrofluoric acid is act as a Bronsted Lowry-acid because it donate one hydrogen ion to $H_2O$ and $H_3O^+$ is act as a Bronsted Lowry-base because it accept one hydrogen ion from $HF$ .

8 0

3 years ago