Triangle sign in chemical reaction expression Is it OK to write the triangle below or above the arrow Still have chemical property, lively is inert

Triangle sign in chemical reaction expression Is it OK to write the triangle below or above the arrow Still have chemical property, lively is inert

Generally, when there is catalyst, the triangle should be written below,
If you don't have a catalyst, you have to write it on it,
Triangle represents heating
Lively means easy to react, inactive means not easy to react, Dan is not inert

Find a symbolic expression of chemical reaction
(heated) fresh milk + lemon juice (or vinegar) → cheese + a water like substance (said to be very nutritious)

The ingredient is whey (rich in calcium)

Finding the [literal expression] and [symbolic expression] of chemical reaction formula
1. Magnesium combustion
2. Carbon
3. Phosphorus
4. Iron
5. Sulfur
6. Manganese dioxide
7. Potassium permanganate
8、2H2+O2__ Ignite___ 2H2O what is this?

1. Magnesium + oxygen ignition magnesium oxide (MgO)
2. Carbon + oxygen ignition carbon dioxide (CO2) + water (H2O)
3. Phosphorus + oxygen ignition phosphorus pentoxide (P2O5)
4. Iron + oxygen ignition Fe3O4
5. Sulfur + oxygen ignition sulfur dioxide (SO2)
6. Hydrogen peroxide manganese dioxide (catalyst) - oxygen (O2) + water (H2O)
7. Potassium permanganate heating potassium permanganate + manganese dioxide + oxygen
8. It's water

Write a symbolic expression for the formation of water in a chemical reaction
If it's a chemical reaction

O2 + 2h2 = = 2H2O the number after the letter is small, and the number above the equal sign is ignited

Happy oral 4.9 written multiplication 7 (urgent)
3. Expand the rectangular nursery as shown in the figure below into a rectangular square nursery with side length. (1) what is the area after expansion?

Area = 90 * 90 = 8100 square meters, original rectangular area = 90 * 65 = 5850 square meters, increased area after expansion = 8100-5850 = 2250 square meters

PEP fourth grade mental arithmetic problem card 89 90

Write hard, the foundation of mathematics is very important, especially oral arithmetic. In the future life, if you master mathematics, you can avoid being cheated. And if you have strong oral arithmetic ability in the future exam, you will have more time to think about the exam questions
Let me give you another example. In the civil service examination, there are many math problems in the subject of administrative ability. The reason for this examination is that you can't finish the problems. If you pass the oral arithmetic, you can do more problems in more time. Isn't this more chance than others? Oral arithmetic is time. Remember this sentence and study hard. Come on!

The answer of mental arithmetic question card

Problem solving

The answers to the mental arithmetic card in Volume 2 of grade 3

There it is

Fifth grade volume two oral arithmetic problem card

640÷80=8
15×5= 75
23×3=69
12×2×5= 120
480÷80=6
16×5=80
27×3= 81
90÷15= 6
48÷4= 12
640÷16= 40
39÷3= 13
24×20= 480
32×3= 96
48÷16= 3
12×8= 96
27×3= 81
56÷14= 4
24÷8= 3
14×2= 28
83－45=38
560÷80= 7
96÷24= 4
40÷20=2
40×30= 1200
37＋26= 63
76－39= 37
605＋59= 664
30×23= 690
12×8= 96
27＋32= 59
48＋27= 75
4500×20= 90000
73＋15 = 88
120×600 = 72000
200×360= 72000
6800×400=2720000
280＋270= 450
4×2500= 10000
6000÷40= 150
5×1280= 6400
4.3＋2.7＝ 7
0.75＋0.25＝ 1
4－0.26＝ 3.74
0.35＋2.7＝ 3.07
4.6－1.9＝ 2.7
0.83－0.3＝ 0.53
3＋0.05＝ 3.05
7.2－3.8＝ 3.4
0.07＋0.6＝ 0.67
1.39－0.39＝ 1
10－5.4＝ 4.6
25.6＋23＝ 48.6

Answers to the mental arithmetic question card 37-39 in Volume 2 of grade 5

Please say the title! If you are like this, others who don't have this book can't help you answer!
This is the answer to the mental arithmetic card in Volume 2 of grade 5 of Beijing Normal University Edition
640÷80=8
15×5= 75
23×3=69
12×2×5= 120
480÷80=6
16×5=80
27×3= 81
90÷15= 6
48÷4= 12
640÷16= 40
39÷3= 13
24×20= 480
32×3= 96
48÷16= 3
12×8= 96
27×3= 81
56÷14= 4
24÷8= 3
14×2= 28
83－45=38
560÷80= 7
96÷24= 4
40÷20=2
40×30= 1200
37＋26= 63
76－39= 37
605＋59= 664
30×23= 690
12×8= 96
27＋32= 59
48＋27= 75
4500×20= 90000
73＋15 = 88
120×600 = 72000
200×360= 72000
6800×400=2720000
280＋270= 450
4×2500= 10000
6000÷40= 150
5×1280= 6400
4.3＋2.7＝ 7
0.75＋0.25＝ 1
4－0.26＝ 3.74
0.35＋2.7＝ 3.07
4.6－1.9＝ 2.7
0.83－0.3＝ 0.53
3＋0.05＝ 3.05
7.2－3.8＝ 3.4
0.07＋0.6＝ 0.67
1.39－0.39＝ 1
10－5.4＝ 4.6
25.6＋23＝ 48.6