I love maths and computer science, so does that mean I am in moha? Or attached to worldly things which not good in path of reaching god?
No. One has to definitely work according to his Swa-Dharma and indulge in worldly actions and fulfill his desires. As life stages pass on, he will understand these actions which are motivated by fruits of desire yield temporary results and hence should persue the path for Moksha. Or one may work in non attachment by renouncing fruits of action.
It is not right to be absorbed in desires—But there is in this world, no absolute absence of desire; for the study of the Vedas itself is prompted by desire, as also every act prescribed in the Veda(Manu 2.2)
Of the strong, I am the strength devoid of desire and attachment, and in all beings, I am the desire unopposed to Dharma, O Arjuna.(BG 7.11)
Spiritual merit and wealth are called good; or pleasure and wealth; or spiritual merit alone, or wealth alone is good; but the truth is that it is the aggregate of the three.(Manu 2.224)
Acts which secure [the fulfilment of] desires in this world or in the next are called pravritta; but acts performed without any desire [for a reward], preceded by wisdom, are declared to be nivritta.(Manu 12.89)
Performing verily works in this world one should wish to live a hundred years. Thus it is right for thee and not otherwise than this. Action will not bind that man.(Isa Upanishad 2)
O Arjuna, when one discards all selfish desires and cravings of the senses that torment the mind, and becomes satisfied in the realization of the self, such a person is said to be transcendentally situated.(BG 2.55)
Do thou fight for the sake of fighting, without considering happiness or distress, loss or gain, victory or defeat – and by so doing you shall never incur sin(BG 2.38)
To work alone you have the right, and not to the fruits. Do not be impelled by the fruits of work. Nor have attachment to inaction.(BG2.47)
The spirit soul bewildered by the influence of false ego thinks himself the doer of activities that are in actuality carried out by the three modes of material nature.(BG 3.27)
Those who see action in inaction and inaction in action are truly wise amongst humans. Although performing all kinds of actions, they are yogis and masters of all their actions.(BG 4.18)
He who is satisfied with gain which comes of its own accord, who is free from duality and does not envy, who is steady in both success and failure, is never entangled, although performing actions. (BG 4.22)
He who is devoted to the path of action, whose mind is it pure, who has conered the self, who has subdued his senses and who realizes his Self as the Self in all beings, though acting, is not tainted.(BG 5.7)
Does that mean I am in Moha?
Well, It depends. If you are obsessed with it and can even stake other important things for it then you are definitely under the clutches of this venomous serpent called MOHA.
But generally When You know the things which you need to do as a dutiful student and in that pursuit, you develop an interest then it's okay until and unless it becomes an obstacle in the path to seek GOD. It is advised to dovetail our activities in such a way that it serves the lord. If you do good in your studies you can always employ your knowledge and money to disseminate the lord's teachings.
The point is when you get attached to things or people, you will remember them. But when you remember God and do things as your duty then you will be free from the clutches of Maya and will be taken care by the lord
Whatever state of being one remembers when he quits his body, that state he will attain without fail. (BG 8.6)
Therefore, always remember Me and also do your duty of fighting the war. With mind and intellect surrendered to Me, you will definitely attain Me; of this, there is no doubt. (BG 8.7)
You need to understand the difference between love and lust(doesn't only have a sexual connotation but a general desire to satisfy your senses). It is said that Pure Love doesn' exist in this world and it can only be with the lord and whatever we call love is actually lust.
When we say that I love someone or something we actually mean to say that we enjoy doing or being with it. In other words, That person/thing pleases my senses in some way or the other.
Material nature consists of the three modes - goodness, passion and ignorance. When the living entity comes in contact with nature, he becomes conditioned by these modes.(BG 14.5)
The mode of passion is born of unlimited desires and longings, O son of Kunti, and because of this one is bound to material fruitive activities.(BG 14.7)
Yes, It means you are in Moha, you should not love or hate anything and should be neutral with everything.
I can give you many examples how can it be a moha, for example, if you love maths or CS that means you are able to solve the problems easily or you are learning something new every time, But this will create a false ego and feeling of superiority or inferiority complex, which will again make you go far away from god.
Also take another example suppose someone says bad of maths or CS that it is totally rubbish subjects then you will feel bad or may create anger in your heart these things again will make you far away from God.
Let me complete with last example that suppose at present time due to MOHA you feel you are in love with thsese subjects but no one know it will continue, or not. at some time when these subjects will bring suffering to you you may feel hate.
Therefore any type of attachment is MOHA, stay away from it.