1. Questions

Science

CHECK MY ANSWERS!!!!!!!
1) Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct?(1 point)

A. The model should show 27 protons and 32 neutrons.******
B. The model should show 59 protons and 27 neutrons.
C. The model should show 27 protons and 27 neutrons.
D. The model should show 32 protons and 59 neutrons.

2) In a molecule of lithium sulfide, there are two atoms of lithium and one atom of sulfur. Which statement about lithium sulfide is correct?(1 point)

A) The chemical formula for lithium sulfide is LiS2.
B) The atoms in lithium sulfide are held together by bonds.*****
C) Both lithium and sulfur form positive ions.
D) A molecular model of lithium sulfide would have two spheres.

3)Which element has the same number of valence electrons as bromine (Br)? (1 point)
A) ytterbium (Yb)
B) selenium (Se)
C) krypton (Kr)******
D) astatine (At)

4) Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
A) They have similar reactivity.*******
B) They are both hard and brittle.
C) They have similar atomic weights.
D) They are both colorless.

5) A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point)
A) It is a chemical change because there is no phase change.
B) It is a chemical change because the size changes.
C) It is a physical change because the process is reversible.
D) It is a physical change because there is no reaction.******

6) How are chemical changes different from physical changes?(1 point)
A) They form new substances.********
B) They are reversible.
C) They involve heat.
D) They include shifts in the phase of matter.

7)A scientist makes several observations about a chemical reaction and records them in the table shown. Which observation contains an error? (1 point) picture added!
A) 1
B) 3
C) 2******
D) 4

8) In a chemical reaction, hydrofluoric acid (HF) and sodium hydroxide (NaOH) combine to form sodium fluoride (NaF) and water (H2O). The reaction uses 20 grams of hydrofluoric acid and 40 grams of sodium hydroxide, and it produces 18 grams of water. How much sodium fluoride does the reaction produce?(1 point)

A) 60 grams
B) 42 grams
C) 18 grams******
D) 78 grams

9)Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)

A) Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
B) Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.********
C) Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
D) Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

10) One molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine in a reaction. How many atoms are in the products?(1 point)

A) two******
B) four
C) three
D) six

11) Use the unbalanced chemical equation to answer the question.

2NaHCO3 → Na2CO3 + CO2

What can be added to the products to balance the equation? (1 point)

A) CH2OH****
B) H2O
C) H2
D) O2

12) The chemical formula for phosphorus trichloride is PCl3. In one to two sentences, explain how you would build a ball-and-stick model of phosphorus trichloride. Include a description of the parts of the model.(2 points)

13) Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the chemical equation. A scientist adds 4 grams of Cu to 2 grams of S to start the reaction. At the end of the experiment, she has 6 grams of product. In one to two sentences, explain what would happen if the scientist increased the amount of copper to 6 grams, and why. (1 point)

  1. 👍 0
  2. 👎 0
  3. 👁 2,256
☆Alexa☆

  1. I'm befuddled. This is the same question(s) Damon and I answered yesterday including the same typos, omitted information, etc. What goes?

    1. 👍 0
    2. 👎 0
    👨‍🏫
    DrBob222

  2. im sorry but i cant find the question

    1. 👍 1
    2. 👎 0
    ☆Alexa☆

  4. It's one of the many problems brought on by the changes in this forum. Sorry you lost it. For fear of you losing it again, I will try to repost this question at the top of the page, answer it, and perhaps you will see it before it disappears.

    1. 👍 0
    2. 👎 0
    👨‍🏫
    DrBob222

  5. I reposted the entire question at the top of the page under "science--repost for Alexa by DrBob222. It may not be the first question by the time you look at it but it will be somewhere near the top of the page.

    1. 👍 0
    2. 👎 0
    👨‍🏫
    DrBob222

  6. Are these correct

    1. 👍 0
    2. 👎 1
    Anonymous

  8. im sorry but ever since jiskha got updated i really cant find a ton of questions

    1. 👍 1
    2. 👎 0
    ☆Alexa☆

  9. are These wrong

    1. 👍 1
    2. 👎 0
    Anonymous

  10. are they correct

    1. 👍 0
    2. 👎 1
    blob

  12. are they correct or not?

    1. 👍 0
    2. 👎 1
    karen mill

  13. ARE THEY CORRECT I NEED TO KNOW NOW

    1. 👍 0
    2. 👎 1
    answer me darnit

  14. @answer me darnit nope she is wrong

    1. 👍 0
    2. 👎 1
    popi ;)

  16. bruvvvvvv is this correct or not i really need to knowwwww

    1. 👍 0
    2. 👎 0
    Lynn

  17. idk @popi;)

    1. 👍 0
    2. 👎 0
    hAi ThErE

  18. uh....are they correct or wrong...which one's are correct and which one's are wrong? Please let me know!!!!

    1. 👍 0
    2. 👎 0
    honey bunny

  20. honey bunny which ones are right

    1. 👍 0
    2. 👎 0
    lol

  21. first of all what are the answers

    1. 👍 0
    2. 👎 0
    jay

  22. for connexus kids
    1. b
    2. b
    3. b
    4. c
    5. c
    6. a
    7. b
    8. b
    9. c
    10. c
    11. d
    12 and 13 you answer on yr own < 33

    1. 👍 2
    2. 👎 8
    uhhhh

  24. is they right

    1. 👍 0
    2. 👎 0
    nick

  25. is uhhhh correct

    1. 👍 0
    2. 👎 2
    Anonymous

  26. are they right ?

    1. 👍 0
    2. 👎 1
    a

  28. has anyone actually taken it yet and found out the correct answers?

    1. 👍 0
    2. 👎 0
    Anonymous

  29. uhhhhh is definitely not correct at all i got two right 😭😭the ones taht she does have right are 7 which is b and 8 which is also b.

    Correct answers are
    1.c
    2.c
    3.a
    4.b
    5.a
    6.c
    7.b
    8.b
    9.b
    10.d
    11.c
    and then the last two are on your own. Yw btw

    1. 👍 1
    2. 👎 5
    Katelyn

  30. There all randomized what are The acttually word answers?

    1. 👍 2
    2. 👎 0
    Yuhh

  32. yo katelyn all those answers are wrong

    1. 👍 1
    2. 👎 0
    anonymous

  33. there randomized smh so prob not correct.....maybe sum

    1. 👍 0
    2. 👎 0
    lil peep forever~🐣🖤😔🥺

  34. @uhhh is completely worng

    1. 👍 0
    2. 👎 0
    Yuhh

  36. alexa, your answers were mostly wrong. i got wrong answers. to anyone who sees this, DONT USE HER ANSWERS.

    1. 👍 2
    2. 👎 0
    helpful person

  37. Someone please help Im really confused and I bet all of y'all are too

    1. 👍 0
    2. 👎 0
    Frustrated

  38. 1. The model should show 27 protons and 32 neutrons.
    2. The atoms in lithium sulfide are held together by bonds.
    3. astatine (At)
    4. They have similar reactivity
    5. It is a physical change because there is no reaction.
    6. They form new substances
    7. 1
    8. 42 grams
    9. Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
    10.six
    11. H20
    12 and 13 on your own:)

    1. 👍 17
    2. 👎 0
    :)

  40. what is right can people just say what the answer is or questions and not just spam pleasd

    1. 👍 0
    2. 👎 0
    Connexus Student

  41. :) is right!!! tysm

    1. 👍 0
    2. 👎 0
    connexus

  42. Yay! Thank you :)!

    1. 👍 0
    2. 👎 0
    AngelYou_tube12

  44. I really need help with 12! Can someone pls help me?

    1. 👍 4
    2. 👎 0
    Connexus girl

  45. @Connexus girl, i would but im also stuck on that question right now.

    1. 👍 1
    2. 👎 0
    crdfhncsdghbk

  46. answers]

    1. 👍 0
    2. 👎 0
    Bella

  48. The answer that :) forgot to type is 2, it is actually question 8, I guess they shifted

    1. 👍 0
    2. 👎 0
    Trash

  49. man I don't understand 13 AT ALL

    1. 👍 0
    2. 👎 0
    Tired

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    An element has three stable isotopes. One has a mass number of 63 and an abundance of 50%. The second has a mass number of 65 and an abundance of 30%. The third has a mass number of 67 and an abundance of 20%. Calculate the

  2. science

    Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct?

  3. Science--HELP!!

    Can you please check my answers: 1. Dalton's idea that atoms cannot be divided into smaller parts was disproved by the discovery of _________ (electrons?) 2. The description of the structure of the atom is called ______ (atomic

  4. Science

    The Composition of Atoms Quick Check questions and answers Science 8 A Unit 3: Matter Interactions A. A model of an atom shows eight electrons in rings that represent different energy levels. How many electrons are in each energy

  1. Chemistry

    What is the nuclear charge of an atom with a mass of 23 and an atomic number of 11? (1) 11+ (2) 12+ (3) 23+ (4) 34+ How do you figure this out? Would the answer be (1) 11+ since the atomic number is 11 and atomic #=protons which

  2. Science

    if an atom has 17 electrons and its mass number is 35, calculate the following: number of protons, atomic number, and number of neutrons. i think there would be: an atomic number of 17, there would be 17 protons, and there would

  3. Chemistry-Bonding

    Classify the following bonds as ionic, covalent, or neither (O, atomic number 8; F, atomic number 9; Na, atomic number 11; Cl, atomic number 17; U, atomic number 92). a.) O with F _________ b.) Ca with Cl __________ c.) Na with Na

  4. science

    1.the modern atomic model includes orbiting the nucleus. which of the following parts of dalton's was disproved by the discovery of the electron atoms are tiny particles atoms cannot be divided into smaller parts atoms have

  1. science

    HELP ME !!!!!!! What is the atomic number of an atom?(1 point) the number of particles in the nucleus the number of protons the number of neutrons the number of particles outside the nucleus Which statement about an atom is

  2. Chemistry

    Write a brief passage describing a neutral atom of nitrogen-14 (N-14). Describe the number of protons, neutrons, and electrons in the atom, where each type of particle is located, and how the terms atomic number, mass number, and

  3. Science

    1. Which statement about subatomic particles is NOT true? (1 point) Protons and neutrons have almost the same mass. Protons and electrons have opposite charges. Unlike protons and electrons, neutrons have no charge. Protons and

  4. Science

    Using the periodic table and your knowledge of atomic structure. cobalt (Co) and nickel (Ni) have almost identical atomic mass numbers. Comparing the a typical nickel and cobalt atoms, which statement best describes the atoms? A)

You can view more similar questions or ask a new question.